Flexible display panel and flexible display apparatus

ABSTRACT

A flexible display panel and a display apparatus are provided. The flexible display panel includes a flexible substrate, a first buffer layer disposed on one side of the flexible substrate, a thin-film transistor layer disposed on a side of the first buffer layer away from the flexible substrate, a planarization layer disposed on a side of the thin-film transistor layer away from the flexible substrate, and an organic light-emitting layer disposed on a side of the planarization layer away from the flexible substrate, where the flexible display panel includes at least one bending area, and in the at least one bending area, at least one groove is formed in at least one of the first buffer layer and the thin-film transistor layer, and 
     
       
         
           
             W 
             ≥ 
             
               
                 n 
                 
                   180 
                   ° 
                 
               
               ⁢ 
               π 
               ⁢ 
               
                   
               
               ⁢ 
               
                 R 
                 .

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part (CIP) application of U.S.patent application Ser. No. 15/895,491, filed on Feb. 13, 2018, whichclaims priority to U.S. patent application Ser. No. 15/497,792, filed onApr. 26, 2017, which claims the priority to Chinese Patent ApplicationNo. CN201611238279.2, filed on Dec. 28, 2016, the entire contents of allof which are incorporated herein by reference.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to the display technology and,more particularly, relates to a flexible display panel and a flexibledisplay apparatus.

BACKGROUND

Emerging flexible display technology has gained a lot of attention. Whenbending an existing flexible display panel, due to the thickness of theflexible display panel, a substantially large bending stress isgenerated in the flexible display panel. The substantially large bendingstress easily causes cracks or even breakage in the bending area of thedisplay panel.

The disclosed flexible display panel and flexible display apparatus aredirected to solve one or more problems set forth above and otherproblems.

BRIEF SUMMARY OF THE DISCLOSURE

One aspect of the present disclosure provides a flexible display panel.The flexible display panel includes a flexible substrate, a first bufferlayer disposed on one side of the flexible substrate, a thin-filmtransistor layer disposed on a side of the first buffer layer away fromthe flexible substrate, a planarization layer disposed on a side of thethin-film transistor layer away from the flexible substrate, and anorganic light-emitting layer disposed on a side of the planarizationlayer away from the flexible substrate. The flexible display panelincludes at least one bending area, and in the at least one bendingarea, at least one groove is formed in at least one of the first bufferlayer and the thin-film transistor layer. A bottom width W of the atleast one groove is configured to be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$where n is a maximum bending angle of the at least one bending area, 0°<

≤180°, and R is a bending radius of the at least one bending area.

Another aspect of the present disclosure provides a flexible displayapparatus including the disclosed flexible display panel.

Other aspects of the present disclosure can be understood by thoseskilled in the art in light of the description, the claims, and thedrawings of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are merely examples for illustrative purposesaccording to various disclosed embodiments and are not intended to limitthe scope of the present disclosure.

FIG. 1A illustrates a cross-sectional view of an existing display panel;

FIG. 1B illustrates a cross-sectional view of an exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 1C illustrates a cross-sectional view of an exemplary bent flexibledisplay panel according to disclosed embodiments;

FIG. 1D illustrates a cross-sectional view of another exemplary bentflexible display panel according to disclosed embodiments;

FIG. 2A illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 2B illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 2C illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 3A illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 3B illustrates a top view of another exemplary flexible displaypanel according to disclosed embodiments;

FIG. 4A illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 4B illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 4C illustrates a top view of another exemplary flexible displaypanel according to disclosed embodiments;

FIG. 4D illustrates a top view of another exemplary flexible displaypanel according to disclosed embodiments;

FIG. 5 illustrates a schematic view of an exemplary display apparatusaccording to disclosed embodiments;

FIG. 6A illustrates a flow chart of an exemplary flexible display panelfabrication method according to disclosed embodiments;

FIG. 6B illustrates cross-sectional views of an exemplary flexibledisplay panel corresponding to each step of an exemplary fabricationmethod according to disclosed embodiments;

FIG. 6C illustrates a flow chart of another exemplary flexible displaypanel fabrication method according to disclosed embodiments;

FIG. 6D illustrates a flow chart of another exemplary flexible displaypanel fabrication method according to disclosed embodiments;

FIG. 7A illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 7B illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 7C illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 7D illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 7E illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 7F illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 7G illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 8A illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 8B illustrates a top view of another exemplary flexible displaypanel according to disclosed embodiments;

FIG. 8C illustrates a top view of another exemplary flexible displaypanel according to disclosed embodiments;

FIG. 8D illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 8E illustrates a top view of another exemplary flexible displaypanel according to disclosed embodiments;

FIG. 9A illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 9B illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 9C illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 9D illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 10 illustrates a schematic view of another exemplary displayapparatus according to disclosed embodiments;

FIG. 11A illustrates a flow chart of another exemplary flexible displaypanel fabrication method according to disclosed embodiments;

FIG. 11B illustrates cross-sectional views of an exemplary flexibledisplay panel corresponding to various steps of another exemplaryfabrication method according to disclosed embodiments;

FIG. 11C illustrates a flow chart of another exemplary flexible displaypanel fabrication method according to disclosed embodiments;

FIG. 11D illustrates a flow chart of another exemplary flexible displaypanel fabrication method according to disclosed embodiments;

FIG. 12 illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 13 illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 14 illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 15 illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 16 illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 17 illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments;

FIG. 18 illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments; and

FIG. 19 illustrates a top view of another exemplary flexible displaypanel according to disclosed embodiments.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary embodiments of thedisclosure, which are illustrated in the accompanying drawings. Whereverpossible, the same reference numbers will be used throughout thedrawings to refer to the same or like parts. It should be understoodthat the exemplary embodiments described herein are only intended toillustrate and explain the present invention and not to limit thepresent invention. In addition, it should also be noted that, for easeof description, only part, but not all, of the structures associatedwith the present invention are shown in the accompanying drawings. Allother embodiments obtained by those skilled in the art without makingcreative work are within the scope of the present invention.

The present disclosure will now be described in detail with reference tothe accompanying drawings. When illustrating the embodiments of thepresent disclosure, certain areas of the schematic views of the devicestructures may be disproportionally enlarged for the convenience ofillustration. In addition, the three-dimensional sizes including thelength, width, and depth should be included in the actual implementationof the present disclosure.

FIG. 1A illustrates a cross-sectional view of an existing display panel.As shown in FIG. 1A, the existing display panel often includes asubstrate 100, a thin-film-transistor layer 200 disposed on thesubstrate 100, an organic light-emitting layer 300 disposed on thethin-film-transistor layer 200, a thin-film-encapsulation layer 400disposed on the organic light-emitting layer 300, a polarization layer500 disposed on the thin-film-encapsulation layer 400, and a coveragewindow disposed on the polarization layer 500.

The thin-film-encapsulation layer 400 includes a first encapsulationsub-layer 420 and a second encapsulation sub-layer 440. The firstencapsulation sub-layer 420 is formed by an organic insulation material.The second encapsulation sub-layer 440 is formed by a resin material. Aportion of the second encapsulation sub-layer 440 in a bending area isremoved for reducing the bending stress. However, when bending theflexible display panel, the bending stress tends to concentrate in theareas 600 and, thus, the bending stress in the bending area may not beeffectively reduced. Further, the removal of the portion of the secondencapsulation sub-layer 440 in the bending area may significantlydegrade the encapsulation of the thin-film-encapsulation layer 400.

The present disclosure provides an improved flexible display panel. Theflexible display panel may include a flexible substrate, an organiclight-emitting layer disposed on a side of the flexible substrate andhaving a first side facing the flexible substrate and an opposing side,and a thin-film-encapsulation layer disposed on the opposing side of theorganic light-emitting layer. The thin-film-encapsulation layer mayinclude at least one organic encapsulation layer and at least oneinorganic encapsulation layer. The organic encapsulation layer may havea first side facing the organic light-emitting layer and an opposingside. The flexible display panel may include at least one bending area,where at least one groove may be formed on the opposing side of the atleast one organic encapsulation layer. A width W at the bottom (i.e.,the bottom width) of the groove may be configured to be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$where n is a maximum bending angle of the bending area, 0°<

≤180°, and R is a bending radius of the bending area.

FIG. 1B illustrates a cross-sectional view of an exemplary flexibledisplay panel according to disclosed embodiments. As shown in FIG. 1B,the flexible display panel may include a flexible substrate 11, anorganic light-emitting layer 12 disposed on a side of the flexiblesubstrate 11 and having a first side facing the flexible substrate andan opposing side, and a thin-film-encapsulation layer 13 disposed on theopposing side of the organic light-emitting layer 12. Thethin-film-encapsulation layer 13 may include an inorganic encapsulationlayer 131 and an organic encapsulation layer 132. The organicencapsulation layer 132 may have a first side facing the organiclight-emitting layer 12 and an opposing side.

The flexible display panel may include at least one bending area S. Theorganic encapsulation layer 132 in the bending area S may be formed withat least one groove 14 on the opposing side. The bottom width W of thegroove 14 may be configured to be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$where

is a maximum bending angle of the bending area, 0°<

≤180°, and R is a bending radius of the bending area.

In the disclosed embodiments, because at least one organic encapsulationlayer in the bending area S is formed with at least one groove 14 on theopposing side, the thickness of the flexible display panel at thebending area S may be reduced and, accordingly, the bending stressgenerated in the bending area S of the flexible display panel may bereduced. Moreover, when the bottom width W of the groove 14 isconfigured to be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$the bending stress generated in the bending area S of the flexibledisplay panel may not concentrate at the groove 14 and, accordingly, theintensity of the bending stress may be reduced, and certain portion ofthe bending stress in the groove 14 may be relieved.

In addition, the disclosed flexible display panel may reduce the bendingstress by reducing the thickness of certain sub-layers of thethin-film-encapsulation layer, instead of completely removing certainsub-layers of the thin-film-encapsulation layer in the existing flexibledisplay panel. Thus, the bending stress in the bending area may still beeffectively reduced and, meanwhile, ambient moisture and oxygen may beeffectively prevented from entering the organic light-emitting layerthrough the thin-film-encapsulation layer, thereby ensuring theencapsulation of the thin-film-encapsulation layer.

As shown in FIG. 1B, the thin-film-encapsulation layer 13 may includeone inorganic encapsulation layer 131 and one organic encapsulationlayer 132, which is for illustrative purposes and is not intended tolimit the scope of the present disclosure. In another embodiment, thenumber of the inorganic encapsulation layers and the number of theorganic encapsulation layers each may be configured to be greater than1.

Referring to FIG. 1B, the organic light-emitting layer 12 may include aplurality of organic light-emitting devices arranged in array. Theorganic light-emitting device may include any appropriate organiclight-emitting devices. In one embodiment, the organic light-emittingdevice may include a first electrode, an organic light-emitting layer,and a second electrode, which are stacked sequentially. Athin-film-transistor layer may be disposed between the organiclight-emitting layer 12 and the flexible substrate 11. Thethin-film-transistor layer may include a plurality ofthin-film-transistors, storage capacitors, data lines, gate lines, powersupply voltage lines, and ground lines, etc.

The thin-film-encapsulation layer 13 may be configured to encapsulatethe organic light-emitting device and the thin-film-transistors. Thethin-film-encapsulation layer 13 may prevent ambient moisture and oxygenfrom entering the organic light-emitting devices, thereby protecting theorganic light-emitting devices. The thin-film-encapsulation layer 13 mayalso protect the thin-film-transistors.

In one embodiment, the organic encapsulation layer 132 may be made ofany one of acrylic, epoxy, and silicone material. The organicencapsulation layer 132 may be formed by an ink jet printing process.The ink jet printing is simple and reliable, through which the organicencapsulation layer 132 may be formed without masks. The inorganicencapsulation layer 131 may be formed by a chemical vapor deposition(CVD) or atomic layer deposition (ALD) process.

FIG. 1C illustrates a cross-sectional view of an exemplary bent flexibledisplay panel according to disclosed embodiments. As shown in FIG. 1C,the flexible display panel may include three areas, a first area A1, abending area S, and a second area A2. The bending area S may be locatedbetween the first area A1 and the second area A2, and the bending area Smay be adjacent to and in contact with the first area A1 and the secondarea A2. That is, the first area A1 and the second area A2 may beextension areas on both sides of the bending area S.

A bending angle of the bending area S may be defined as a bending angleα of the second area A2 with respect to the first area A1. The bendingradius R may be defined as a shortest distance between a center of thecircle formed by the bending area S and the bottom of the groove 14. Thebending R radius may be greater than or equal to about 0.1 mm. When thebending radius R is smaller than 0.1 mm, the flexible display panel maynot be bent easily. Excessive bending stress may occur in the bendingarea S, thereby increasing the risk of the flexible display panelbreakage. When the bending radius R is greater than or equal to 0.1 mm,the bending stress in the bending area S may be substantially small,thereby reducing the risk of the flexible display panel breakage.

FIG. 1D illustrates a cross-sectional view of another exemplary bentflexible display panel according to disclosed embodiments. As shown inFIG. 1D, the flexible display panel may be bent to a position having abending angle of about 180° of the bending area S. Because the groove 14is formed on the organic encapsulation layer 132 and is corresponding tothe bending area S, the thickness of the flexible display panel in thebending area S may be reduced, and the bending stress in the bendingarea S of the flexible display panel may be reduced.

In addition, because the bottom width W of the groove 14 is configuredto be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$i.e., W≥πR, and a first climbing position 201 and a second climbingposition 202 may be located just outside the bending area S, the bendingstress in the bending area S may not concentrate at the first climbingposition 201 and the second climbing position of the groove 14. Thus,the organic encapsulation layer 132 may be prevented from cracking orbreaking at the first climbing position 201 and the second climbingposition 202.

The organic encapsulation layer 132 may be disposed in the bending areaS. The organic encapsulation layer 132 and the inorganic encapsulationlayer 131 disposed in the bending area S may be coordinated toeffectively block ambient moisture and oxygen, thereby reducing thebending stress in the bending area S and, meanwhile, ensuring theeffective encapsulation of the thin-film-encapsulation layer 13 in thebending area S.

Further, in one embodiment, the width of the bottom of the groove 14 maybe configured to W=πR. Because the groove 14 is formed in the bendingarea S, when the bottom width of the groove 14 is configured to be W=πR,the bottom width of the groove 14 may be equal to a width of the bendingarea S, thereby reducing the bending stress in the bending area S and,meanwhile, ensuring the effective encapsulation of thethin-film-encapsulation layer 13.

Returning to FIG. 1B, in one embodiment, the organic encapsulation layer132 formed with the groove 14 may have a thickness d2 of approximatelybetween 2 μm and 40 μm, and the groove 14 may have a thickness d1 ofapproximately between 1 μm and 20 μm. The organic encapsulation layer132 may relieve the bending stress generated between the inorganicencapsulation layers 131 and increase invasion paths of moisture andoxygen. However, when the organic encapsulation layer 132 issubstantially thick, the neutral plane may be deviated from the organiclight-emitting layer 12, damaging the organic light-emitting layer 12when bending the flexible display panel, and degrading displayperformance. In addition, when the organic encapsulation layer 132 issubstantially thick, the bending radius may increase. Thus, the organicencapsulation layer 132 formed with the groove 14 may be configured tohave the thickness d2 of approximately between 2 μm and 40 μm and thegroove 14 may be configured to have the thickness d1 of approximatelybetween 1 μm and 20 μm.

FIG. 2A illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. The similaritiesbetween FIG. 2A and FIG. 1B are not repeated here, while certaindifferences will be explained.

As shown in FIG. 2A, the organic encapsulation layer 132 may furtherinclude a first organic encapsulation sub-layer 1321 and a secondorganic encapsulation sub-layer 1322. The first organic encapsulationsub-layer 1321 may be continuously disposed to cover the entire flexibledisplay panel. The second organic encapsulation sub-layer 1322 may bediscontinued in the bending area S, thereby forming at least one groove14.

FIG. 2B illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. In another embodiment,as shown in FIG. 2B, the flexible display panel may include a flexiblesubstrate 11, an organic light-emitting layer 12 disposed on a side ofthe flexible substrate 11 and having a first side facing the flexiblesubstrate and an opposing side, a thin-film-encapsulation layer 13disposed on the opposing side of the organic light-emitting layer 12.The thin-film-encapsulation layer 13 may include a first inorganicencapsulation layer 131, a second inorganic encapsulation layer 133, anda first organic encapsulation layer 132 disposed between the firstinorganic encapsulation layer 131 and the second inorganic encapsulationlayer 133. The first inorganic encapsulation layer 131 may be disposedbetween the organic light-emitting layer 12 and the first organicencapsulation layer 132. The first organic encapsulation layer 132 maybe formed with at least one groove 14 in the bending area S.

The first inorganic encapsulation layer 131 and the second inorganicencapsulation layer 133 may easily have cracks when being bent, due tothe material properties of inorganic encapsulation layers. Throughconfiguring the first organic encapsulation layer 132 to have at leastone groove 14 formed in the bending area S, the bending stress may bereduced. Accordingly, the second inorganic encapsulation layer 133disposed on the first organic encapsulation layer 132 may be preventedfrom cracking or breaking caused by excessive bending stress when beingbent, and the encapsulation effectiveness of the thin-film-encapsulationlayer 13 may be ensured.

FIG. 2C illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. The similaritiesbetween FIG. 2C and FIG. 1B are not repeated here, while certaindifferences will be explained.

As shown in FIG. 2C, the flexible display panel may include a flexiblesubstrate 11, an organic light-emitting layer 12 disposed on a side ofthe flexible substrate 11 and having a first side facing the flexiblesubstrate and an opposing side, a thin-film-encapsulation layer 13disposed on the opposing side of the organic light-emitting layer 12.The thin-film-encapsulation layer 13 may include a first inorganicencapsulation layer 131, a first organic encapsulation layer 132, asecond inorganic encapsulation layer 133, a second organic encapsulationlayer 134, and a third inorganic encapsulation layer 135.

Either the first organic encapsulation layer 132 or the second organicencapsulation layer 134 may be configured with at least one groove 14 inthe bending area S, such that the bending stress may be reduced, and atleast one of the second inorganic encapsulation layer 133 disposed onthe first organic encapsulation layer 132 and the third inorganicencapsulation layer 135 disposed on the second organic encapsulationlayer 134 may be prevented from cracking or breaking caused by anexcessive bending stress when being bent. Employing three inorganicencapsulation layers and two organic encapsulation layers may ensure theencapsulation effectiveness of the thin-film-encapsulation layer 13, andmay improve the life span of the flexible display panel.

FIG. 3A illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. The similaritiesbetween FIG. 3A and FIG. 1B are not repeated here, while certaindifferences will be explained.

As shown in FIG. 3A, the flexible display panel may further include atleast one of a first curved line 151 and a second curved line 152. Thefirst curved line 151 may be disposed transitioning between the bottomof the groove 14 and the side wall of the groove 14, and the secondcurved line 152 may be disposed transitioning between the side wall ofthe groove 14 and the non-recessed surface of the organic encapsulationlayer 132.

The transition between the bottom of the groove 14 and the side wall ofthe groove 14 may be smoothed through the first curved line 151. Whenbeing bent, the bending stress at the bottom and on the side wall of thegroove 14 may be further reduced. Thus, the risk of cracks in theorganic encapsulation layer 132 may be further reduced, and the bendingperformance of the flexible display panel when being bent may beimproved.

An angle α formed between the first curved line 151 and the bottom ofthe groove 14 may be determined according to various applicationscenarios. In one embodiment, the angle α formed between the firstcurved line 151 and the bottom of the groove 14 may be greater thanabout 0° and smaller than or equal to about 70°, i.e., 0°<α≤70°. Inanother embodiment, the angle α formed between the first curved line 151and the bottom of the groove 14 may be greater than about 15° andsmaller than or equal to about 70°, i.e., 15°<α≤70°. When the angle αformed between the first curved line 151 and the bottom of the groove 14is large, for example, greater than about 70° and smaller than or equalto about 90°, a substantially large bending stress may be generated whenthe flexible display panel is bent. The bending stress may likelyconcentrate in the groove 14, thereby causing the groove 14 to crack orbreak.

When the angle α formed between the first curved line 151 and the bottomof the groove 14 is sustainably small, the bottom width of the groove 14may be sustainably wide, and the groove 14 may extend into the displayarea of the flexible display panel, thereby causing the light emittedfrom the display area to refract and reflect and degrading the displayperformance of the flexible display panel. Thus, the angle α formedbetween the first curved line 151 and the bottom of the groove 14 may beconfigured to be approximately greater than about 15° and smaller thanor equal to about 70°, i.e., 15°<α≤70°.

Similarly, an angle β formed between the second curved line 152 and thenon-recessed surface of the organic encapsulation layer 132 may bedetermined according to various application scenarios. In oneembodiment, the angle β formed between the second curved line 152 andthe non-recessed surface of the organic encapsulation layer 132 may begreater than about 0° and smaller than or equal to about 60°, i.e.,0°<β≤60°. In another embodiment, the angle β formed between the secondcurved line 152 and the non-recessed surface of the organicencapsulation layer 132 may be greater than about 15° and smaller thanor equal to about 70°, i.e., 15°<β≤70°. When the angle β formed betweenthe second curved line 152 and the non-recessed surface of the organicencapsulation layer 132 is large, for example, greater than about 70°and smaller than or equal to about 90°, a substantially large bendingstress may be generated when the flexible display panel is bent. Thebending stress may likely concentrate in the groove 14, thereby causingthe groove 14 to crack or break.

When the angle β formed between the second curved line 152 and thenon-recessed surface of the organic encapsulation layer 132 issubstantially small, the bottom width of the groove 14 may be wide, andthe groove 14 may extend into the display area of the flexible displaypanel, thereby causing the light emitted from the display area torefract and reflect, and degrading the display performance of theflexible display panel. Thus, the angle β formed between the secondcurved line 152 and the non-recessed surface of the organicencapsulation layer 132 may be configured to be greater than about 15°and smaller than or equal to about 45°, i.e., 15°<β≤45°.

In the disclosed embodiments, one bending area may include a pluralityof grooves. That is, a plurality of grooves may be disposed in the samebending area. When the plurality of the grooves is configured in thesame bending area, the plurality of the grooves may be arranged inparallel in a direction perpendicular to an extension direction of thegroove. An exemplary structure is shown in FIG. 3B.

FIG. 3B illustrates a top view of another exemplary flexible displaypanel according to disclosed embodiments. As shown in FIG. 3B, onebending area of the flexible display panel may include two grooves 14.The grooves 14 may extend in a direction Y. The two grooves 14 may bearranged in parallel in a direction X. The direction X may beperpendicular to the extension direction Y of grooves 14. The number ofthe grooves 14, the directions X and Y in FIG. 3B are for illustrativepurposes and are not intended to limit the scope of the presentdisclosure.

The flexible display panel may include a display area and a non-displayarea surrounding the display area. At least one of the display area andthe non-display area may be configured with at least one bending area.The display area may be an area for image display, and the non-displayarea may be an area not for image display.

Further, the non-display area of the flexible display panel may bedisposed with a peripheral circuit. An orthogonal projection of theperipheral circuit onto the flexible substrate may partially overlapwith an orthogonal projection of the bending area onto the flexiblesubstrate. An exemplary structure is shown in FIG. 4A.

FIG. 4A illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. As shown in FIG. 4A,the flexible display panel may include a display area B1 and anon-display area B2. The non-display area B2 of the flexible displaypanel may be configured with a peripheral circuit 16. An orthogonalprojection of the peripheral circuit 16 onto the flexible substrate 11may partially overlap with an orthogonal projection of the bending areaS onto the flexible substrate 11. Thus, the bending area S may notseparately occupy the non-display area B2 of the flexible display panel,thereby facilitating a narrow frame design of the flexible displaypanel.

The peripheral circuit may include thin-film-transistors and metalwirings. That is, the bending area S may bend downwards from the edge ofthe display area B1, and may be located in the non-display area B2. Invarious practical applications, after the bending area S is bent, thenon-display area B2 may become a side wall of the flexible displaypanel. When the flexible display panel is incorporated in a displayapparatus, the bending area S may be bent, such that the non-displayarea B2 may become a side wall of the display apparatus, or thenon-display area B2 may be folded to the back wall of the display areaB1. Thus, a borderless design of the display apparatus may be achieved,and non-display area B2 may be called an edge area or border area.

FIG. 4B illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. In one embodiment, asshown in FIG. 4B, the flexible display panel may include a flexiblesubstrate 11, an organic light-emitting layer 12 disposed on a side ofthe flexible substrate 11 and having a first side facing the flexiblesubstrate and an opposing side, and a thin-film-encapsulation layer 13disposed on the opposing side of the organic light-emitting layer 12.The thin-film-encapsulation layer 13 may include a first inorganicencapsulation layer 131, a second inorganic encapsulation layer 133, anda first organic encapsulation layer 132. The first organic encapsulationlayer 132 may be disposed between the first inorganic encapsulationlayer 131 and the second inorganic encapsulation layer 133. The firstinorganic encapsulation layer 131 may be disposed between the organiclight-emitting layer 12 and the first organic encapsulation layer 132.The first organic encapsulation layer 132 may be configured with atleast one groove 14 in the bending area S.

The flexible display panel may also include a display area. The displayarea may include a first display area A1 and a second display area A2.Both the first display area A1 and the second display area A2 may belocated adjacent to the bending area S. The bending area S may bedisposed between the first display area A1 and the second display areaA2. That is, the bending area S may also be located in the display area.However, the bending area S may be located in a non-light-emitting areaof the display area.

In particular, an orthogonal projection of the groove 14 on the organiclight-emitting layer 12 may be located between two adjacent rows or twoadjacent columns of sub-pixels. That is, in a direction perpendicular tothe flexible display panel, the thin-film-encapsulation layer 13 in thearea of sub-pixels may not be configured with any groove 14. Thus, thearea of sub-pixels in the thin-film-encapsulation layer 13 may besubstantially flat, such that the optical properties of the sub-pixelsby the groove 14 may not be degraded by the groove 14.

In another embodiment, as shown in FIG. 4B, the flexible display panelmay include a flexible substrate 11, an organic light-emitting layer 12disposed on a side of the flexible substrate 11 having a first sidefacing the flexible substrate and an opposing side, and athin-film-encapsulation layer 13 disposed on the opposing side of theorganic light-emitting layer 12. The thin-film-encapsulation layer 13may include a first inorganic encapsulation layer 131, a secondinorganic encapsulation layer 133, and a first organic encapsulationlayer 132. The first organic encapsulation layer 132 may be disposedbetween the first inorganic encapsulation layer 131 and the secondinorganic encapsulation layer 133. The first inorganic encapsulationlayer 131 may be disposed between the organic light-emitting layer 12and the first organic encapsulation layer 132. The first organicencapsulation layer 132 may be configured with at least one groove 14 inthe bending area S.

The flexible display panel may also include a first display area A1 anda second display area A2. The first display area A1 and the seconddisplay area A2 may display different images. The bending area S may bedisposed between the first display area A1 and the second display areaA2. That is, the bending area S may bend downwards from an edge of thefirst display area A1. The bending area S may be a non-display area. Thesecond display area A2 may be an area extended outward from the bendingarea S. In various practical applications, when the flexible displaypanel is incorporated in a display apparatus, the flexible display panelmay display different images in the first display area A1 and the seconddisplay area A2. Thus, the display apparatus may be a double-sideddisplay apparatus.

FIG. 4C illustrates a top view of another exemplary flexible displaypanel according to disclosed embodiments. As shown in FIG. 4C, aplurality of grooves 14 may be disposed between two adjacent columns ofpixels 17. The groove 14 may be arranged in a straight line in anextension direction of the groove 14. That is, the groove 14 may have astraight line shape.

FIG. 4D illustrates a top view of another exemplary flexible displaypanel according to disclosed embodiments. As shown in FIG. 4D, aplurality of grooves 14 may be disposed between any two adjacent columnsof pixels 17. The groove 14 may be arranged in a folded line in anextension direction of the groove 14. That is, the groove 14 may have afolded line shape.

The arrangement and the shape of the grooves 14 in FIG. 4C and FIG. 4Dare for illustrative purposes and are not intended to limit the scope ofthe present disclosure.

In practical applications, the grooves 14 may be arranged in a wayadapting to the shape and arrangement of the pixels.

The present disclosure also provides a display apparatus. The displayapparatus may include a disclosed flexible display panel. FIG. 5illustrates a schematic view of an exemplary display apparatus accordingto disclosed embodiments. As shown in FIG. 5, the display apparatus 51may include a flexible display panel 52. The flexible display panel 52may be any one of the disclosed flexible display panels. Although asmart phone is shown in FIG. 16, the touch control display apparatus 1may be a smart watch, a VR goggle, a smart hand band, an electronicpaper, a television set, an automotive display, a notebook computer, atablet computer, or any appropriate touch control display apparatus,which is not limited by the present disclosure.

FIG. 6A illustrates a flow chart of an exemplary fabrication method foran exemplary flexible display panel according to disclosed embodiments.FIG. 6B illustrates cross-sectional views of an exemplary flexibledisplay panel corresponding to each step of an exemplary fabricationmethod according to disclosed embodiments. As shown in FIG. 6A, at thebeginning, a flexible substrate is provided (S610). After the flexiblesubstrate is provided, an organic light-emitting layer is formed on theflexible substrate (S620). The corresponding structure is shown in FIG.6B.

As shown in FIG. 6B, the organic light-emitting layer 12 may be formedby sputtering, vapor deposition, or similarly appropriate processes. Inparticular, through sputtering or vapor deposition, a first electrode ofan organic light-emitting device may be formed in the organiclight-emitting layer 12 on the flexible substrate 11. The firstelectrode may have a first side facing the flexible substrate and anopposing side. After the first electrode is formed, through sputteringor vapor deposition, an organic light-emitting material layer may beformed on the opposing side of the first electrode. The organiclight-emitting material layer may have a first side facing the flexiblesubstrate and an opposing side. After the organic light-emittingmaterial layer is formed, through sputtering or vapor deposition, asecond electrode may be formed on the opposing side of the organiclight-emitting material layer. The first electrode or the secondelectrode may be a transparent electrode, a semi-transparent electrode,or a reflective electrode.

Returning to FIG. 6A, after the organic light-emitting layer is formedon the flexible substrate, the organic light-emitting layer has a firstside facing the flexible substrate and an opposing side, athin-film-encapsulation layer is formed on the opposing side of theorganic light-emitting of the flexible substrate (S630). Thecorresponding structure is shown in FIG. 6B.

As shown in FIG. 6B, the organic light-emitting layer 12 may have afirst side facing the flexible substrate 11 and an opposing side. Thethin-film-encapsulation layer 13 may be formed on the opposing side ofthe organic light-emitting layer 12. The thin-film-encapsulation layer13 may include at least one organic encapsulation layer 132 and at leastone inorganic encapsulation layer 131. The organic encapsulation layer132 may have a first side facing the flexible substrate 11 and anopposing side. The inorganic encapsulation layer 131 may have a firstside facing the flexible substrate 11 and an opposing side. Thefabricated flexible display panel may include at least one bending area.At least one groove may be formed on the opposing side of at least oneorganic encapsulation layer 132 in the bending area.

A bottom width W of the groove may be configured to be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$where n is a maximum bending angle of the bending area, 0°<

≤180°, and R is a bending radius of the bending area. In one embodiment,the bottom width W of the groove may be configured to be W=πR.

In the disclosed embodiments, the organic encapsulation layer 132 mayformed by an ink jet printing process. The organic encapsulation layer132 may be formed together with the groove by the same ink jet printingprocess. The inorganic encapsulation layer 131 may be formed by achemical vapor deposition (CVD) process or an atomic layer deposition(ALD) process.

FIG. 6C illustrates a flow chart of another exemplary fabrication methodfor an exemplary flexible display panel according to disclosedembodiments. The corresponding structure is shown in FIG. 6B. Thesimilarities between FIG. 6C and FIG. 6A are not repeated here, whilecertain differences will be explained.

As shown in FIG. 6C, at the beginning, a flexible substrate is provided(S611). After the flexible substrate is provided, an organiclight-emitting layer is formed on a side of the flexible substrate(S612). After the organic light-emitting layer is formed on the flexiblesubstrate, an inorganic encapsulation layer is formed on the opposingside of the organic light-emitting layer (S613). After the inorganicencapsulation layer is formed on the organic light-emitting layer,through ink jet printing, a first organic encapsulation sub-layer isformed continuously on the opposing side of the inorganic encapsulationlayer, and then a second organic encapsulation sub-layer is formed onthe opposing side of the first organic encapsulation layer, and at leastone groove is formed by discontinuing the second organic encapsulationsub-layer in the bending area (S614).

The inorganic encapsulation layer may be disposed between the organiclight-emitting layer and the first organic encapsulation sub-layer.

FIG. 6D illustrates a flow chart of another exemplary fabrication methodfor an exemplary flexible display panel according to disclosedembodiments. The corresponding structure is shown in FIG. 6B. Thesimilarities between FIG. 6D and FIG. 6A are not repeated here, whilecertain differences will be explained.

As shown in FIG. 6D, at the beginning, a flexible substrate is provided(S621). After the flexible substrate is provided, an organiclight-emitting layer is formed on a side of the flexible substrate(S622). After the organic light-emitting layer is formed on the flexiblesubstrate, an inorganic encapsulation layer is formed on opposing sideof the organic light-emitting layer (S623). After the inorganicencapsulation layer is formed on the organic light-emitting layer,through ink jet printing, an organic encapsulation layer is formed onthe opposing side of the inorganic encapsulation layer, and at least onegroove is formed by discontinuing the organic encapsulation layer in thebending area (S624).

The inorganic encapsulation layer may be disposed between the organiclight-emitting layer and the organic encapsulation layer. Through inkjet printing, the organic encapsulation layer and at least one groovemay be formed at the same time.

In the disclosed embodiments, for example, as shown in FIG. 2A-6D, thedisplay panel may include a flexible substrate, an organiclight-emitting layer disposed on a side of the flexible substrate andhaving a first side facing the flexible substrate and an opposing side,and a thin-film-encapsulation layer disposed on the opposing side of theorganic light-emitting layer. The thin-film-encapsulation layer mayinclude at least one organic encapsulation layer and at least oneinorganic encapsulation layer. The organic encapsulation layer may havea first side facing the organic light-emitting layer and an opposingside. The flexible display panel may include at least one bending area,where at least one groove may be formed on the opposing side of the atleast one organic encapsulation layer. A width W at the bottom (i.e.,the bottom width) of the groove may be configured to be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$where n is a maximum bending angle of the bending area, 0°<

≤180°, and R is a bending radius of the bending area.

Because the organic encapsulation layer is substantially thick, throughconfiguring at least one groove on the opposing side of at least oneorganic encapsulation layer in the bending region and, meanwhile,configuring the width W of the bottom surface of the groove to be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$the thickness of the flexible display panel may be reduced in at least apart of the bending area, and the film layers in the bending area mayget closer to the neutral surface. Accordingly, the bending stressgenerated at the bending area of the flexible display panel may bereduced, and the encapsulation effect of the thin-film-encapsulationlayer may be ensured.

In the thin-film-encapsulation layer, the inorganic encapsulation layeroften has excellent moisture and oxygen barrier properties but issubstantially rigid. The organic encapsulation layer has poorer moistureand oxygen barrier properties than the inorganic encapsulation layer butis able to eliminate the stress generated by the inorganic encapsulationlayer. Due to the material properties of the inorganic encapsulationlayers in the thin-film-encapsulation layer, the inorganic encapsulationlayer may easily have cracks when being bent.

The present disclosure further provides a flexible display panel whereat least one groove may be formed on at least one inorganicencapsulation layer in the bending area, thereby preventing theinorganic encapsulation layer from having cracks when being bent.

The display panel may include a flexible substrate, an organiclight-emitting layer disposed on a side of the flexible substrate andhaving a first side facing the flexible substrate and an opposing side,and a thin-film-encapsulation layer disposed on the opposing side of theorganic light-emitting layer. The thin-film-encapsulation layer mayinclude at least one organic encapsulation layer and at least oneinorganic encapsulation layer. The inorganic encapsulation layer mayhave a first side facing the organic light-emitting layer and anopposing side. The flexible display panel may include at least onebending area, and at least one groove may be formed on the opposing sideof the at least one organic encapsulation layer in the bending area. Awidth W at the bottom (i.e., the bottom width) of the groove may beconfigured to be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$where n is a maximum bending angle of the bending area, 0°<

≤180°, and R is a bending radius of the bending area.

FIG. 7A illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments.

As shown in FIG. 7A, the flexible display panel may include a flexiblesubstrate 11, an organic light-emitting layer 12, and athin-film-encapsulation layer 13. The organic light-emitting layer 12may be disposed on a side the flexible substrate 11. The organiclight-emitting layer 12 may have a first side facing the flexiblesubstrate and an opposing side, and thin-film-encapsulation layer 13 maybe disposed on the opposing side of the organic light-emitting layer 12.

The thin-film-encapsulation layer 13 may include at least one organicencapsulation layer and at least one inorganic encapsulation layer. Theat least one inorganic encapsulation layer may have a first side facingthe organic light-emitting layer and an opposing side. At least onebending area may be disposed on the opposing side of the at least oneinorganic encapsulation layer.

The bottom width W of the groove 14 may be configured to be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$where

is a maximum bending angle of the bending area, 0°<

≤180°, and R is a bending radius of the bending area. In one embodiment,bottom width W of the groove 14 may be configured to be W≥πR.

In the disclosed embodiments, because at least one inorganicencapsulation layer in the bending area S is formed with at least onegroove 14 on the opposing side, the thickness of the flexible displaypanel at the bending area S may be reduced, and the bending stressgenerated in the bending area S of the flexible display panel may bereduced. Thus, the risk of cracks or even breaks in the flexible displaypanel and, more particular, in the inorganic encapsulation layer of thethin film encapsulation layer, may be reduced. Moreover, when the bottomwidth W of the groove 14 is configured to be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$the bending stress generated in the bending area S of the flexibledisplay panel may not concentrate at the groove 14 and, accordingly, theintensity of the bending stress may be reduced, and certain portion ofthe bending stress in the groove 14 may be relieved.

In one embodiment, the bottom width W of the groove 14 may be configuredto be W≥πR, such that corners of the groove 14 may be arranged outsidethe bending area S, and the stress may be prevented from beingconcentrated at the corners of the groove 14. Accordingly, cracks andbreaks may be suppressed at the corners of the groove 14.

In one embodiment, as shown in FIG. 7A, the thin-film-encapsulationlayer 13 may include a first inorganic encapsulation layer 131, a secondinorganic encapsulation layer 133, and a first organic encapsulationlayer 132. The first organic encapsulation layer 132 may be disposedbetween the first inorganic encapsulation layer 131 and the secondinorganic encapsulation layer 133. The first inorganic encapsulationlayer 131 may be disposed between the thin-film-transistor layer 18 andthe first organic encapsulation layer 132. The flexible display panelmay include at least one bending area S. The first inorganicencapsulation layer 131 may have a first side facing the flexiblesubstrate 11 and an opposing side, and at least groove 14 may bedisposed on the opposing side of the first inorganic encapsulation layer131 in the bending area S.

In addition, the flexible panel may further include athin-film-transistor layer 18 disposed between the organiclight-emitting layer 12 and the flexible substrate 11. Thethin-film-transistor layer 18 may include a plurality ofthin-film-transistors (TFT), storage capacitors, data lines, gate lines,power supply voltage lines, and ground lines, etc. In particular, thedata lines, gate lines, power supply voltage lines, and ground lines maybe disposed in a wiring region in the thin-film-transistor layer 18. TheTFT may drive a corresponding organic light-emitting device to emitlight, thereby displaying images. The thin-film-encapsulation layer 13may be configured to encapsulate the organic light-emitting device andthe thin-film-transistors and, meanwhile, prevent ambient moisture andoxygen from entering the organic light-emitting devices, therebyprotecting the organic light-emitting devices.

The first inorganic encapsulation layer 131 and the second inorganicencapsulation layer 133 may easily have cracks when being bent, due tothe material properties of inorganic encapsulation layers. Throughconfiguring the first inorganic encapsulation layer 131 with at leastone groove 14 formed in the bending area S, the thickness of theflexible display panel at the bending area S may be reduced, and thebending stress may be reduced. Accordingly, the first inorganicencapsulation layer 131 may be prevented from cracking or breakingcaused by excessive bending stress when being bent, the bendingreliability of the flexible display panel may be enhanced, and theencapsulation effectiveness of the thin-film-encapsulation layer 13 maybe ensured.

In certain embodiments, one bending area may include a plurality ofgrooves. That is, a plurality of grooves may be disposed in the samebending area. When the plurality of the grooves is configured in thesame bending area, the plurality of the grooves may be arranged inparallel in a direction perpendicular to an extension direction of thegroove.

The flexible display panel may also include a display area. The displayarea may include a first display area A1 and a second display area A2.Both the first display area A1 and the second display area A2 may belocated adjacent to the bending area S. The bending area S may bedisposed between the first display area A1 and the second display areaA2. That is, the bending area S may also be located in the display area.However, the bending area S may be located in a non-light-emitting areaof the display area.

In particular, an orthogonal projection of the groove 14 on the organiclight-emitting layer 12 may be located between two adjacent rows or twoadjacent columns of sub-pixels. That is, in a direction perpendicular tothe flexible display panel, the thin-film-encapsulation layer 13 may notbe configured with any groove 14 in the area of sub-pixels. Thus, thearea of sub-pixels in the thin-film-encapsulation layer 13 may besubstantially flat, such that the optical properties of the sub-pixelsby the groove 14 may not be degraded by the groove 14.

In one embodiment, the first display area A1 and the second display areaA2 may display different images. The bending area S may be disposedbetween the first display area A1 and the second display area A2. Thatis, the bending area S may bend downwards from an edge of the firstdisplay area A1. The bending area S may be a non-display area. Thesecond display area A2 may be an area extended outward from the bendingarea S. In various practical applications, when the flexible displaypanel is incorporated in a display apparatus, the flexible display panelmay display different images in the first display area A1 and the seconddisplay area A2. Thus, the display apparatus may be a double-sideddisplay apparatus.

Referring to FIG. 7A, the flexible display panel may further include atleast one of a first curved line 151 and a second curved line 152. Thefirst curved line 151 may be disposed transitioning between the bottomof the groove 14 and the side wall of the groove 14, and the secondcurved line 152 may be disposed transitioning between the side wall ofthe groove 14 and the non-recessed surface of the first inorganicencapsulation layer 131.

The transition between the bottom of the groove 14 and the side wall ofthe groove 14 may be smoothed through the first curved line 151. Whenbeing bent, the bending stress at the bottom and on the side wall of thegroove 14 may be further reduced. Thus, the risk of cracks in the firstinorganic encapsulation layer 131 may be further reduced, and thebending performance of the flexible display panel when being bent may beimproved.

It should be noted that, FIG. 7A shows the first curved line 151 may bedisposed transitioning between the bottom of the groove 14 and the sidewall of the groove 14, and the second curved line 152 may be disposedtransitioning between the side wall of the groove 14 and thenon-recessed surface of the first inorganic encapsulation layer 131,which is for illustrative purposes and is not intended to limit thescope of the present disclosure.

In another embodiment, the flexible display panel may include at leastone of the following: a bottom of the at least one groove transitions toa side wall of the at least one groove through a first curved line; andthe side wall of the at least one groove transitions to a non-recessedsurface of the at least one organic encapsulation layer through a secondcurved line. Thus, the risk of cracks in the inorganic encapsulationlayer may be further reduced, and the bending performance of theflexible display panel when being bent may be improved.

In particular, referring to FIG. 7A, an angle α formed between the firstcurved line 151 and the bottom of the groove 14 may be determinedaccording to various application scenarios. In one embodiment, the angleα formed between the first curved line 151 and the bottom of the groove14 may be greater than about 0° and smaller than or equal to about 70°,i.e., 0°<α≤70°. In another embodiment, the angle α formed between thefirst curved line 151 and the bottom of the groove 14 may be greaterthan about 15° and smaller than or equal to about 70°, i.e., 15°<α≤70°.

When the angle α formed between the first curved line 151 and the bottomof the groove 14 is large, for example, greater than about 70° andsmaller than or equal to about 90°, a substantially large bending stressmay be generated when the flexible display panel is bent. The bendingstress may likely concentrate at the corners of the groove 14, i.e.,where the angle α between the first curved line 151 and the bottom ofthe groove 14 is formed or where the angle β between the second curvedline 152 and the non-recessed surface of the first inorganicencapsulation layer 131 is formed. When the corners of the groove 14 aresteep slopes or sharp corners, cracks or even breaks may be likely tooccur at the steep slopes or sharp corners.

When the angle α formed between the first curved line 151 and the bottomof the groove 14 is sustainably small, the bottom width of the groove 14may be sustainably wide, and the groove 14 may extend into the displayarea of the flexible display panel, thereby causing the light emittedfrom the display area to refract and reflect and degrading the displayperformance of the flexible display panel. Thus, the angle α formedbetween the first curved line 151 and the bottom of the groove 14 may beconfigured to be approximately greater than about 15° and smaller thanor equal to about 70°, i.e., 15°<α≤70°.

Similarly, an angle β formed between the second curved line 152 and thenon-recessed surface of the first inorganic encapsulation layer 131 maybe determined according to various application scenarios. In oneembodiment, the angle β formed between the second curved line 152 andthe non-recessed surface of the first inorganic encapsulation layer 131may be greater than about 0° and smaller than or equal to about 60°,i.e., 0°<β≤60°. In another embodiment, the angle formed between thesecond curved line 152 and the non-recessed surface of the firstinorganic encapsulation layer 131 may be greater than about 15° andsmaller than or equal to about 70°, i.e., 15°<β≤70°.

When the angle β formed between the second curved line 152 and thenon-recessed surface of the first inorganic encapsulation layer 131 islarge, for example, greater than about 70° and smaller than or equal toabout 90°, a substantially large bending stress may be generated whenthe flexible display panel is bent. The bending stress may likelyconcentrate at the corners of the groove 14, thereby causing the groove14 to crack or break.

When the angle β formed between the second curved line 152 and thenon-recessed surface of the first inorganic encapsulation layer 131 issubstantially small, the bottom width of the groove 14 may be wide, andthe groove 14 may extend into the display area of the flexible displaypanel, thereby causing the light emitted from the display area torefract and reflect, and degrading the display performance of theflexible display panel. Thus, the angle β formed between the secondcurved line 152 and the non-recessed surface of the first inorganicencapsulation layer 131 may be configured to be greater than about 15°and smaller than or equal to about 45°, i.e., 15°<β≤45°.

FIG. 7B illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. The similaritiesbetween FIG. 7A and FIG. 7B are not repeated here, while certaindifferences may be explained.

As shown in FIG. 7B, the flexible display panel may include a displayarea B1 and a non-display area B2. The non-display area B2 of theflexible display panel may be configured with a peripheral circuit 16.The flexible display panel may include at least one bending area S. Thesecond inorganic encapsulation layer 132 may have a first side facingthe flexible substrate 11 and an opposing side, and at least groove 14may be disposed on the opposing side of the second inorganicencapsulation layer 132 in the bending area S.

Further, an orthogonal projection of the peripheral circuit 16 onto theflexible substrate 11 may partially overlap with an orthogonalprojection of the bending area S onto the flexible substrate 11. Thus,the bending area S may not separately occupy the non-display area B2 ofthe flexible display panel, thereby facilitating a narrow frame designof the flexible display panel.

In various practical applications, after the bending area S is bent, thenon-display area B2 may become a side wall of the flexible displaypanel. When the flexible display panel is incorporated in a displayapparatus, the bending area S may be bent, such that the non-displayarea B2 may become a side wall of the display apparatus, or thenon-display area B2 may be folded to the back wall of the display areaB1. Thus, a borderless design of the display apparatus may be achieved,and non-display area B2 may be called an edge area or border area.

FIGS. 7A-7B illustrates that the thin-film-encapsulation layer 13 mayinclude two inorganic encapsulation layers and one organic encapsulationlayer, and at least groove 14 may be disposed on the opposing side ofthe first inorganic encapsulation layer 131 in the bending area S, whichis for illustrative purposes and is not intended to limit the scope ofthe present disclosure. In another embodiment, the number of theinorganic encapsulation layers and the number of the organicencapsulation layers each may be configured to be larger than 1, andmore than one inorganic encapsulation layer may be configured with thegroove. Exemplary structures are shown in FIGS. 7C-7G.

FIG. 7C illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. The similaritiesbetween FIG. 7A and FIG. 7C are not repeated here, while certaindifferences may be explained.

As shown in FIG. 7C, the thin-film-encapsulation layer 13 may include afirst inorganic encapsulation layer 131, a first organic encapsulationlayer 132, a second inorganic encapsulation layer 133. The firstinorganic encapsulation layer 131 may be disposed between the organiclight-emitting layer 12 and the first organic encapsulation layer 132,and the first organic encapsulation layer 132 may be disposed betweenthe first inorganic encapsulation layer 131 and the second inorganicencapsulation layer 133.

At least one of the first inorganic encapsulation layer 131 and thesecond inorganic encapsulation layer 133 may be configured with at leastone groove 14 in the bending area S. In one embodiment, as shown in FIG.7C, the first inorganic encapsulation layer 131 and the second inorganicencapsulation layer 133 each may have a first side facing the flexiblesubstrate 11 and an opposing side. In the bending area S, at least onegroove 14 may be disposed on the opposing side of the first inorganicencapsulation layer 131 and the opposing side of the second inorganicencapsulation layer 133.

Due the material properties of the inorganic encapsulation layer, crackseasily occur during bending. Through configuring at least one groove 14on the opposing side of at least one of the first inorganicencapsulation layer 131 and the second inorganic encapsulation layer 133in the bending area S, the stress generated during bending may bereduced. Thus, cracks or even breaks in the first inorganicencapsulation layer 131 and/or the second inorganic encapsulation layer133, which is generated due to the substantially large stress in thefirst inorganic encapsulation layer 131 or the second inorganicencapsulation layer 133, may be suppressed.

It should be noted that, in addition to configuring both the firstinorganic encapsulation layer 131 and the second inorganic encapsulationlayer 133 to be provided with at least one groove 14 in the bending areaS, the first organic encapsulation layer 132 disposed between the firstinorganic encapsulation layer 131 and the second inorganic encapsulationlayer 133 may also be configured with at least one groove 14 in thebenign area S. Thus, in the bending area S, the second inorganicencapsulation layer 133 may get closer to the neutral plane and,accordingly, the bending stress of the second inorganic encapsulantlayer 133 may be further reduced, the risk of bending cracks and breaksmay be reduced, and the encapsulation effect may be further ensured.

FIG. 7D illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. The similaritiesbetween FIG. 7D and FIG. 7C are not repeated here, while certaindifferences may be explained.

As shown in FIG. 7D, the thin-film-encapsulation layer 13 may include afirst inorganic encapsulation layer 131, a first organic encapsulationlayer 132, a second inorganic encapsulation layer 133, a second organicencapsulation layer 134, and a third inorganic encapsulation layer 135,which may be sequentially on the opposing side of the organiclight-emitting layer. At least one of the first inorganic encapsulationlayer 131, the second inorganic encapsulation layer 133 and the thirdinorganic encapsulation layer 135 may be configured with at least onegroove 14 in the bending area S, such that the bending stress may bereduced. Accordingly, the first inorganic encapsulation layer 131, thesecond inorganic encapsulation layer 133 and the third inorganicencapsulation layer 135 may be prevented from cracking or breakingcaused by an excessive bending stress when being bent.

In the bending area S, through configuring at least one groove 14 on theopposing side of the inorganic encapsulation layer, the thickness of theinorganic encapsulation layer may be reduced. In addition, the inorganicencapsulation layer may also be disposed with at least one groove 14 inthe bending area S. Thus, in the bending area, the inorganicencapsulation layer may get closer to the neutral plane and,accordingly, the bending stress of the inorganic encapsulation layer maybe further reduced, the risk of bending cracks and breaks may bereduced, and the encapsulation effect may be further ensured.

Further, employing three inorganic encapsulation layers and two organicencapsulation layers may ensure the encapsulation effectiveness of thethin-film-encapsulation layer 13, and improve the life span of theflexible display panel.

In certain embodiments, the disclosed flexible display panel may reducethe bending stress by reducing the thickness of certain sub-layers ofthe thin-film-encapsulation layer, instead of completely removingcertain sub-layers of the thin-film-encapsulation layer in the existingflexible display panel. Thus, the bending stress in the bending area maystill be effectively reduced and, meanwhile, ambient moisture and oxygenmay be effectively prevented from entering the organic light-emittinglayer through the thin-film-encapsulation layer, thereby ensuring theencapsulation of the thin-film-encapsulation layer. A correspondingstructure is shown in FIG. 7E.

FIG. 7E illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. The similaritiesbetween FIG. 7E and FIG. 7C are not repeated here, while certaindifferences may be explained.

As shown in FIG. 7E, the thin-film-encapsulation layer 13 may include afirst inorganic encapsulation layer 131, a first organic encapsulationlayer 132, a second inorganic encapsulation layer 133. The firstinorganic encapsulation layer 131 may further include a first inorganicencapsulation sub-layer 1311 and a second inorganic encapsulationsub-layer 1312. The first inorganic encapsulation sub-layer 1311 may becontinuously disposed to cover the entire flexible display panel.

The second inorganic encapsulation sub-layer 1312 may be discontinued inthe bending area S or may be continued but have a reduced thickness inthe bending area S as compared the area outside the bending area S(i.e., a non-bending area), thereby forming at least one groove 14. Inone embodiment, as shown in FIG. 7E, the second inorganic encapsulationsub-layer 1312 may be discontinued in the bending area S.

In one embodiment, the first inorganic encapsulation sub-layer 1311 maybe fabricated by an atomic layer deposition (ALD) process, and both thesecond inorganic encapsulation sub-layer 1312 and the second inorganicencapsulation layer 133 may be fabricated by chemical vapor deposition(CVD) process. The second inorganic encapsulation sub-layer 1312 may bediscontinued in the bending area S or may be continued but have areduced thickness in the bending area S as compared the area outside thebending area S (i.e., a non-bending area), thereby forming at least onegroove 14.

After the organic light-emitting layer 12 is prepared, particles or dustmay remain on the surface. Through fabricating the first inorganicencapsulation sub-layer 1311 by an atomic layer deposition (ALD)process, particles or dust may be well covered. Meanwhile, and the filmsfabricated by the ALD process may be substantially rigid with desiredmoisture and oxygen barrier properties. In addition, the film thicknessof the first inorganic encapsulation sub-layer 1311 prepared by the ALDprocess may be substantially thin, such that the first inorganicencapsulation sub-layer 1311 may have substantially good bendingperformance even without disposing with the groove.

After the second inorganic encapsulation sub-layer 1312 is disposed onthe first inorganic encapsulation sub-layer 1311, the encapsulationeffect may be further improved. Furthermore, through disposing at leastone groove 14 on the second inorganic encapsulation sub-layer 1312 inthe bending area, the bending stress generated at the second inorganicencapsulation sub-layer 1312 may be reduced, and the bending performancemay be improved.

In another embodiment, the first inorganic encapsulation sub-layer 1311may be continued but have a reduced thickness in the bending area S ascompared the area outside the bending area S (i.e., a non-bending area),thereby forming at least one groove 14. The first inorganicencapsulation sub-layer 1311 may be fabricated by the chemical vapordeposition (CVD) process. Because the first inorganic encapsulationsub-layer 1311 fabricated by the chemical vapor deposition (CVD) processis substantially thick, a portion of the first inorganic encapsulationsub-layer 1311 may be removed in the bending area to form the groove 14,for example, the thickness of the first inorganic encapsulationsub-layer 1311 may be reduced in the bending area to form the groove 14.

Then the second inorganic encapsulation sub-layer 1312 may be fabricatedby the atomic layer deposition (ALD) process. The films fabricated bythe ALD process may be substantially rigid with desired moisture andoxygen barrier properties. In addition, the film thickness of the firstsecond inorganic encapsulation sub-layer 1312 prepared by the ALDprocess may be substantially thin, such that the second inorganicencapsulation sub-layer 1312 may have substantially good bendingperformance even without disposing with the groove.

FIG. 7F illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. The similaritiesbetween FIG. 7C and FIG. 7E are not repeated here, while certaindifferences may be explained.

As shown in FIG. 7F, the thin-film-encapsulation layer 13 may include afirst inorganic encapsulation layer 131, a first organic encapsulationlayer 132, a second inorganic encapsulation layer 133. Either the firstinorganic encapsulation layer 131 or the second inorganic encapsulationlayer 133 may be configured with at least one groove 14 in the bendingarea S, such that the bending stress may be reduced. In particular, in adirection perpendicular to the flexible substrate 11, the groove 14disposed in the first inorganic encapsulation layer 131 may pass throughthe entire first inorganic encapsulation layer 131. That is, the groove14 disposed in the first inorganic encapsulation layer 131 may have asame thickness as the non-recessed region of the first inorganicencapsulation layer 131.

FIG. 7G illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. The similaritiesbetween FIG. 7G and FIG. 7F are not repeated here, while certaindifferences may be explained.

As shown in FIG. 7G, the first inorganic encapsulation layer 131 and thesecond inorganic encapsulation layer 133 each may be configured with atleast one groove 14 in the bending area S, such that the bending stressmay be reduced. In particular, in a direction perpendicular to theflexible substrate 11, the groove 14 disposed in the first inorganicencapsulation layer 131 may pass through the entire first inorganicencapsulation layer 131, and further extend into a planarization layerdisposed between the organic light-emitting layer 12 and thethin-film-transistor layer 18. In another embodiment, the groove 14disposed in the first inorganic encapsulation layer 131 may even extendinto the thin-film-transistor layer 18, as long as the groove 14 is notin direct contact with the wiring region in the thin-film-transistorlayer 18. Thus, when the flexible display panel is being bent, theencapsulation of the thin-film-encapsulation layer 13 may be furtherensured, while the various wires in the wiring region may not beaffected.

It should be noted that, the groove 14 may extend from the inorganicencapsulation layer to any appropriate layers in the flexible displaypanel, as long as the normal light-emitting function of the organiclight-emitting layer is not affected, signals are normally provided tothe organic light-emitting devices, the organic light-emitting devicesare encapsulated by the inorganic encapsulation layer without affectedby the outside moisture and oxygen, and the encapsulation effect is wellensured. Exemplary structures will be explained in FIG. 8A and FIG. 8D.

In the disclosed embodiments, the number of the inorganic encapsulationlayers which are disposed with at least one groove 14 in the bendingarea S, as well as, the number of the organic encapsulation layers, isfor illustrative purposes and is not intended to limit the scope of thepresent disclosure. In practical applications, thethin-film-encapsulation layer 13 may include a plurality of inorganicencapsulation layers and a plurality of organic encapsulation layersalternately arranged in a direction perpendicular to the flexiblesubstrate 11. The number of the inorganic encapsulation layers, whichare disposed with at least one groove 14 in the bending area S, may bedetermined according to various applications.

In certain embodiments, as shown in FIGS. 7A-7F, the flexible displaypanel may include at least one groove 14 disposed on at least oneinorganic encapsulation layer of the thin-film-encapsulation layer 13 atthe bending area S. In certain other embodiments, in the bending area S,at least one groove 14 may be disposed on a photo spacer disposedbetween the organic light-emitting layer 12 and thethin-film-encapsulation layer 13, the organic light-emitting layer 12, apolarization layer disposed between the organic light-emitting layer 12and the thin-film-transistor layer 18, or the thin-film-transistor layer18.

FIG. 8A illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments.

As shown in FIG. 8A, the flexible display panel may include a flexiblesubstrate 11, a thin-film-transistor layer 18, a planarization layer 15,an organic light-emitting layer 12, and a thin-film-encapsulation layer13. The thin-film-transistor layer 18 may be disposed between theorganic light-emitting layer 12 and the flexible substrate 11. Theplanarization layer 15 may be disposed between the organiclight-emitting layer 12 and thin-film-transistor layer 18. Thethin-film-transistor layer 18 may include a plurality ofthin-film-transistors (TFT) 181, storage capacitors, data lines, gatelines, power supply voltage lines, and ground lines, etc. The organiclight-emitting layer 12 may include a plurality of organiclight-emitting elements 121. The TFT may drive a corresponding organiclight-emitting element 121 to emit light, thereby displaying images.FIG. 8A merely shows two TFTs 181 and two organic light-emittingelements 121 for illustrative purposes.

The organic light-emitting element 121 may include a first electrode 117(e.g., a nontransparent anode or reflective anode), a pixel defininglayer 125, an organic light-emitting material layer 123 and a secondelectrode 119 (e.g., a cathode). The organic light-emitting materiallayer 123 may be disposed between the first electrode 117 and the secondelectrode 119. The pixel defining layer 125 be disposed on theplanarization layer 15 and may have an opening exposing the firstelectrode 117. The organic light-emitting material layer 123 may beformed in a pixel defined by the pixel defining layer 125 and correspondto the opening. Each pixel may include one organic light-emittingelement 121 capable of emitting light in one color, and each organiclight-emitting element 121 may form a light-emitting pixel 17 in FIGS.8B and 8C.

The organic light-emitting material layer 123 may include at least anemission layer and may include at least one of a hole injection layer, ahole transport layer, an electron transport layer, and an electroninjection layer. The pixel defining layer 125 may be an organic layer oran inorganic layer. In one embodiment, the pixel defining layer 125 maybe an organic layer. For example, the material of the pixel defininglayer 125 may include at least one of benzocyclobutene (BCB), acrylpolymer, and polyimide.

The planarization layer 15, which is disposed between the organiclight-emitting layer 12 and thin-film-transistor layer 18, may be anorganic layer, an inorganic layer, or a combination thereof. Forexample, the inorganic layer may be formed of spin on glass (SOG), andthe material of the organic layer may include at least one ofbenzocyclobutene (BCB), acryl polymer, and polyimide.

The TFT 181 driving the organic light-emitting device may include a gateelectrode 111, a source electrode 114_1 and a drain electrode 114_2(i.e., source-drain electrode), a semiconductor active layer 113, and atleast one insulating layer. In one embodiment, as shown in FIG. 8A, theTFT 181 may be a top-gate TFT. The source electrode 114_1, the drainelectrode 114_2, and the semiconductor active layer 113 may be disposedon the flexible substrate 11, a gate insulating layer 112 may bedisposed on the semiconductor active layer 113 and the source electrode114_1 and the drain electrode 114_2, and the gate electrode 111 may bedisposed on a side of the gate insulating layer 112 away from theflexible substrate 11.

In addition, a passivation layer 115 may be disposed on the gateinsulating layer 112 and the gate electrode 111. The first electrode 117of the corresponding organic light-emitting element 121 may beelectrically connected to the drain electrode 114_2 of the TFT 181through a through hole penetrating the passivation layer 115. The gateinsulating layer 112 may include one or more of a silicon oxide film, asilicon nitride film, a silicon nitride oxide film, an aluminum oxidefilm or a titanium oxide film. In the disclosed embodiments, in additionto silicon oxide film, silicon nitride film, silicon nitride oxide film,aluminum oxide film or titanium oxide film, the gate insulating layer112 may also be films formed by other inorganic insulating materialswhich have a same or similar property as the above-mentioned films. Thepassivation layer 115 may include any one of silicon oxide and siliconnitride, or may be a composite layer including both silicon oxide andsilicon nitride.

Further, the flexible display panel may include a plurality of photospacers (PS) (not shown in FIG. 8A) disposed on the pixel defining layer125, and disposed between the organic light-emitting layer 12 and thethin-film-encapsulation layer.

The flexible display panel may include at least one bending area S, andin the benign area, at least one groove is formed on a photo spacer, thepixel defining layer 125 of the organic light-emitting layer 12, the atleast one insulating layer of the thin-film-transistor layer 18, or theplanarization layer 15. The bottom width W of the groove 14 may beconfigured to be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$where n is a maximum bending angle of the bending area, 0°<

≤180°, and R is a bending radius of the bending area.

Thus, the thickness of the flexible display panel may be reduced at thebending area S, and the bending stress generated in the bending area Sof the flexible display panel may be reduced. Accordingly, the flexibledisplay panel may be prevented from cracking or breaking caused by anexcessive bending stress when being bent, and the encapsulationeffectiveness of the thin-film-encapsulation layer 13 may be ensured.

In one embodiment, bottom width W of the groove 14 may be configured tobe W≥πR. Thus, corners of the groove 14 may be arranged outside thebending area S, and the stress may be prevented from being concentratedat the corners of the groove 14. Accordingly, cracks and breaks may besuppressed at the corners of the groove 14.

In one embodiment, as shown in FIG. 8A, the flexible display panel mayinclude at least one bending area S. The pixel defining layer 125 andthe planarization layer 15 each may have a first side facing theflexible substrate 11 and an opposing side far away from the flexiblesubstrate 11. In the bending area, at least groove 14 may be disposed onthe opposing side of the planarization layer 15 and the opposing side ofthe pixel defining layer 125. In addition, the groove 14 may be disposedbetween two adjacent pixels. That is, the orthogonal projection of thegroove 14 onto the flexible substrate 11 may not overlap with theorthogonal projection of any pixel onto the flexible substrate 11.

In one embodiment, as shown in FIG. 8B, a plurality of grooves 14 may beconfigured on the planarization layer 15. Each groove 14 may be disposedbetween any two adjacent columns of pixels 17. Each pixel 17 may includethe organic light-emitting layer 12 capable of emitting light in onecolor. The groove 14 may be arranged in a straight line in an extensiondirection of the groove 14. That is, the groove 14 may have astraight-line shape. In another embodiment, as shown in FIG. 8C, aplurality of grooves 14 may be configured on the pixel defining layer125. Each groove 14 may be disposed between any two adjacent columns ofpixels 17. The groove 14 may be arranged in a folded line in anextension direction of the groove 14. That is, the groove 14 may have afolded line shape.

It should be noted that, the shape of the groove 14 shown in FIGS. 8B-8Care for illustrative purposes and are not intended to limit the scope ofthe present disclosure. As long as the groove 14 is disposed between twoadjacent columns/rows of pixels 17, the groove 14 may have anyappropriate line shape. In practical applications, the grooves 14 may bearranged in a way adapting to the shape and arrangement of the pixels.

Through configuring at least one of the pixel defining layer 125 and theplanarization layer 15 with at least one groove 14 formed in the bendingarea S, the thickness of the flexible display panel at the bending areaS may be reduced, the bending stress may be reduced, and the bendingreliability of the flexible display panel may be enhanced. Because thegroove 14 is disposed between two adjacent pixels 17, the normal displayof the pixel 17 may not be affected.

FIG. 8D illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. The similaritiesbetween FIG. 8A and FIG. 8D are not repeated here, while certaindifferences may be explained.

As shown in FIG. 8D, the flexible display panel may include at least onebending area S. In the bending area, at least groove 14 may be disposedon the at least one insulating layer of the thin-film-transistor layer18.

In one embodiment, as shown in FIG. 8, the passivation layer 115 in theTFT 181 may have a first side facing the flexible substrate 11 and anopposing side far away from the flexible substrate 11, and at least onegroove 14 may be disposed on the opposing side of the passivation layer115 in the bending area S, and the groove 14 may not be in directcontact with the wiring region in the thin-film-transistor layer 18.

Thus, the thickness of the flexible display panel may be reduced at thebending area S, and the bending stress generated in the bending area Sof the flexible display panel may be reduced. Accordingly, the flexibledisplay panel may be prevented from cracking or breaking caused by anexcessive bending stress when being bent. In addition, the firstinorganic encapsulation layer 131 and the passivation layer 15 are indirect contact with each other, and both the first inorganicencapsulation layer 131 and the passivation layer 15 are inorganiclayers. Thus, the first inorganic encapsulation layer 131 and thepassivation layer 15 may have an improved interfacial contact.Accordingly, the peeling or the separation between the first inorganicencapsulation layer 131 and the passivation layer 15 when the flexibledisplay panel is being bent may be suppressed, the moisture and oxygenmay be prevented from entering the organic light-emitting elements atthe separation, and the encapsulation effectiveness of thethin-film-encapsulation layer 13 may be ensured. Meanwhile, because thegroove 14 is not in direct contact with the wiring region in thethin-film-transistor layer 18, the various wires in the wiring regionmay not be affected by the groove 14.

FIG. 8E illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. The similaritiesbetween FIG. 8A and FIG. 8E are not repeated here, while certaindifferences may be explained.

As shown in FIG. 8E, the flexible display panel may include a pluralityof photo spacers (PS) 20 disposed on the pixel defining layer 125 and,more particularly, the spacers (PS) 20 may be disposed between the pixeldefining layer 125 and thin-film-encapsulation layer 13. The spacers 20may be made of, for example, benzocyclobutene (BCB), acryl polymer, orpolyimide. The spacers 20 may serve as points of contact with adeposition mask for depositing the organic light-emitting material. Thespacers 20 may prevent direct contact of constituent elements formed onthe flexible substrate (other than the spacers themselves) with thedeposition mask, and facilitate the depositing of the organiclight-emitting material through the deposition mask to form the organiclight-emitting material layer. The thin-film-encapsulation layer 13 maybe bonded to the flexible substrate 11 to complete the flexible displaypanel.

The flexible display panel may include at least one bending area S, andin the bending area S, at least one spacer 20 may be disposed with atleast one groove 14. In particular, the spacer 20 may have a first sidefacing the flexible substrate 11 and an opposing side far away from theflexible substrate 11, and at least one groove 14 may be disposed on theopposing side of the spacer 20 in the bending area S.

Thus, the thickness of the flexible display panel may be reduced at thebending area S, and the bending stress generated in the bending area Sof the flexible display panel may be reduced. Accordingly, the flexibledisplay panel may be prevented from cracking or breaking caused by anexcessive bending stress when being bent, and the encapsulationeffectiveness of the thin-film-encapsulation layer 13 may be ensured.

In addition, the thickness of the groove 14 may be smaller than or equalto the thickness of the spacer 20. Even the thickness of the groove 14is equal to the thickness of the spacer 20, the support between thethin-film-encapsulation layer 13 and the flexible substrate 11 may notbe degraded because a plurality of spacers 20 are disposed on the pixeldefining layer 125.

In certain embodiments, the groove 14 may pass through the entire spacer20 into the pixel defining layer 125 in the organic-light emitting layer12. In certain other embodiments, the groove 14 may further extend intothe planarization layer 15 arranged between the organic-light emittinglayer 12 and the thin-film-transistor layer 18. In certain otherembodiments, the groove 14 may further extend into passivation layer 115and/or the gate insulating layer 112 in the thin-film-transistor layer18, as long as the groove 14 is not in contact with the wiring region inthe thin-film-transistor layer 18.

The present disclosure further provides a flexible display panel whereat least one groove may be formed in the flexible substrate.

FIG. 9A illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. As shown in FIG. 9A,the flexible display panel may include a flexible substrate 11, athin-film-transistor layer 18, an organic light-emitting layer 12, and athin-film-encapsulation layer 13. The thin-film-transistor layer 18 maybe disposed between the flexible substrate 11 and the organiclight-emitting layer 12. The organic light-emitting layer 12 may have afirst side facing the flexible substrate 1 and an opposing side. Thethin-film-encapsulation layer 13 may be disposed on the opposing side ofthe organic light-emitting layer 12. The thin-film-encapsulation layer13 may include at least one organic encapsulation layer and at least oneinorganic encapsulation layer. In one embodiment, as shown in FIG. 9A,the thin-film-encapsulation layer 13 may include a first inorganicencapsulation layer 131, a second inorganic encapsulation layer 133, anda first organic encapsulation layer 132, which are sequentially disposedon the opposing side of the organic light-emitting layer 12.

The flexible substrate 11 may include a base substrate 1101, an adhesivelayer 1102, and a lower protective layer 1103. The base substrate 1101may be made of any appropriate transparent materials with a desiredflexibility. The adhesive layer 1102 may be made of any appropriateadhesive, such as liquid optically clear adhesive (LOCA), UV curableadhesive. The lower protective film 1103 may be attached to the basesubstrate 1101 through the adhesive layer 1102, thereby protecting theflexible display panel from the lower side.

In one embodiment, the base substrate 1101 may be made of polyimide(PI). Because the PI often has a desired heat resistance, when the TFTsare fabricated on the base substrate 1101 in the subsequent process, thebase substrate 1101 may be able to stand the high temperature requiredfor fabricating the TFTs. The adhesive layer 1102 may include a liquidoptically clear adhesive (LOCA). Liquid optically clear adhesive (LOCA)is often adopted to attach a cover lens or cover glass to a displaypanel in OLEDs and LTPS-LCD (low temperature poly-silicon-LCD). LOCA hasvarious advantages, such as high optical transmittance, good yellowresistance, low cost, good uniformity, and high yield.

The flexible display panel may include at least one bending area S. Inthe flexible substrate 11, at least one of the base substrate 1101, theadhesive layer 1102, and the lower protective layer 1103 may beconfigured with at least one groove 14 in the bending area S. The bottomwidth W of the groove 14 may be configured to be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$where n is a maximum bending angle of the bending area, 0°<

≤180°, and R is a bending radius of the bending area.

In one embodiment, as shown in FIG. 9A, the base substrate 1101 may be asingle polyimide layer. The base substrate 1101 may have a first sidefacing the organic light-emitting layer 12 and an opposing side. Atleast one groove 14 may be disposed on the opposing side of the basesubstrate 1101 in the bending area S. The bottom width W of the groove14 may be configured to be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$where n is a maximum bending angle of the bending area, 0°<

≤180°, and R is a bending radius of the bending area.

Thus, the thickness of the flexible display panel may be reduced at thebending area S, and the bending stress generated in the bending area Sof the flexible display panel may be reduced. Accordingly, the flexibledisplay panel may be prevented from cracking or breaking caused by anexcessive bending stress when being bent, and the encapsulationeffectiveness of the thin-film-encapsulation layer 13 may be ensured.

In one embodiment, bottom width W of the groove 14 may be configured tobe W≥πR. Thus, the base substrate 1101 may have a reduced thickness inthe bending area S, and the climbing position of the groove may belocated just outside the bending area S, the bending stress in thebending area S may not concentrate at the climbing position.

In addition, the flexible display panel may also include a display area.The display area may include a first display area A1 and a seconddisplay area A2. Both the first display area A1 and the second displayarea A2 may be located adjacent to the bending area S. The bending areaS may be disposed between the first display area A1 and the seconddisplay area A2. That is, the bending area S may also be located in thedisplay area, but located in a non-light-emitting area of the displayarea. In particular, an orthogonal projection of the groove 14 on theorganic light-emitting layer 12 may be located between two adjacent rowsor two adjacent columns of sub-pixels.

In one embodiment, the first display area A1 and the second display areaA2 may display different images. The bending area S may be disposedbetween the first display area A1 and the second display area A2. Thatis, the bending area S may bend downwards from an edge of the firstdisplay area A1. The bending area S may be a non-display area. Thesecond display area A2 may be an area extended outward from the bendingarea S. In another embodiment, the bending area S may be located in thenon-light-emitting area of the display area. In particular, anorthogonal projection of the groove 14 on the organic light-emittinglayer 12 may be located between two adjacent rows or two adjacentcolumns of sub-pixels.

FIG. 9B illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. The similaritiesbetween FIG. 9A and FIG. 9B are not repeated here, while certaindifferences may be explained.

As shown in FIG. 9B, the base substrate 1101 may include a firstpolyimide layer 1104, a second polyimide layer 1106, and a buffer layer1105 sandwiched between the first polyimide layer 1104 and the secondpolyimide layer 1106. Through inserting the buffer layer 1105 betweenthe first polyimide layer 1104 and the second polyimide layer 1106, thebending durability of base substrate 1101 may be improved and,meanwhile, the damage to the thin-film-transistors during laser lift-offmay be suppressed. The buffer layer 1105 may be an inorganic layer.

The buffer layer 1105 may have a first side facing the organiclight-emitting layer 12 and an opposing side. At least one groove 14 maybe disposed on the opposing side of the buffer layer 1105 in the bendingarea S. Through introducing the buffer layer 1105 to be sandwichedbetween the first polyimide layer 1104 and the second polyimide layer1106 and configuring the buffer layer 1105 with at least one groove 14formed in the bending area S, the bending stress generated when thebuffer layer 1105 is being bent may be reduced, and the bendingdurability of the flexible display panel may be further improved.

FIG. 9C illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. The similaritiesbetween FIG. 9A and FIG. 9C are not repeated here, while certaindifferences may be explained.

As shown in FIG. 9C, the flexible substrate 11 may include a basesubstrate 1101, an adhesive layer 1102, and a lower protective layer113. The lower protective film 1103 may be attached to the basesubstrate 1101 through the adhesive layer 1102. The adhesive layer 1102may have a first side facing the organic light-emitting layer 12 and anopposing side. The flexible display panel may include at least onebending area S, and at least one groove 14 may be disposed on theopposing side of the adhesive layer 1102 in the bending area S.

The adhesive layer 1102 may be likely to be plastically deformed duringbending, and when the thickness of the adhesive layer 1102 increases,the adhesive layer 1102 may be more likely to be plastically deformedand may be difficult to be restored to the original shape. Throughdisposing at least one groove 14 on the opposing side of the adhesivelayer 1102 in the bending area S, the adhesive layer 1102 may beprevented from being plastically deformed when being bent, and thebending performance may be improved. That is, the desired adhesivenessmay be achieved between the lower protective film 1103 and the basesubstrate 1101, and the bending reliability of the flexible displaypanel may be further enhanced.

FIG. 9D illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. The similaritiesbetween FIG. 9A and FIG. 9D are not repeated here, while certaindifferences may be explained.

As shown in FIG. 9D, the flexible substrate 11 may include a basesubstrate 1101, an adhesive layer 1102, and a lower protective layer113. The lower protective film 1103 may be attached to the basesubstrate 1101 through the adhesive layer 1102. The lower protectivefilm 1103 may have a first side facing the organic light-emitting layer12 and an opposing side. At least one bending area may be disposed onthe opposing side of the lower protective film 1103. The flexibledisplay panel may include at least one bending area S. At least onegroove 14 may be disposed on the opposing side of the lower protectivefilm 1103 in the bending area S.

Through configuring the lower protective film 1103 with at least onegroove 14 formed in the bending area S, the thickness of the flexibledisplay panel at the bending area S may be reduced, and the bendingstress may be reduced. Accordingly, the inorganic encapsulation layersin the thin-film-encapsulation layer 13 may be prevented from crackingor breaking caused by excessive bending stress when being bent, thebending reliability of the flexible display panel may be enhanced.

The present disclosure also provides a display apparatus. The displayapparatus may include a disclosed flexible display panel. FIG. 10illustrates a schematic view of another exemplary display apparatus 1010according to disclosed embodiments. As shown in FIG. 10, the displayapparatus 1010 may include a flexible display panel 1020. The flexibledisplay panel 1020 may be any one of the disclosed flexible displaypanels. Although a smart phone is shown in FIG. 11, the displayapparatus 1010 may be a smart watch, a VR goggle, a smart hand band, anelectronic paper, a television set, an automotive display, a notebookcomputer, a tablet computer, or any appropriate touch control displayapparatus, which is not limited by the present disclosure.

FIG. 11A illustrates a flow chart of another exemplary fabricationmethod for an exemplary flexible display panel according to disclosedembodiments. FIG. 11B illustrates cross-sectional views of an exemplaryflexible display panel corresponding to various step of anotherexemplary fabrication method according to disclosed embodiments.

As shown in FIG. 11A, at the beginning, a flexible substrate is provided(S1110). After the flexible substrate is provided, an organiclight-emitting layer is formed on the flexible substrate (S1120). Thecorresponding structure is shown in FIG. 11B.

As shown in FIG. 11B, the organic light-emitting layer 12 may be formedby sputtering, vapor deposition, or similarly appropriate processes. Inparticular, through sputtering or vapor deposition, a first electrode ofan organic light-emitting device may be formed in the organiclight-emitting layer 12 on the flexible substrate 11. The firstelectrode may have a first side facing the flexible substrate and anopposing side. After the first electrode is formed, through sputteringor vapor deposition, an organic light-emitting material layer may beformed on the opposing side of the first electrode. The organiclight-emitting material layer may have a first side facing the flexiblesubstrate and an opposing side. After the organic light-emittingmaterial layer is formed, through sputtering or vapor deposition, asecond electrode may be formed on the opposing side of the organiclight-emitting material layer. The first electrode or the secondelectrode may be a transparent electrode, a semi-transparent electrode,or a reflective electrode.

Returning to FIG. 11A, after the organic light-emitting layer is formedon the flexible substrate, the organic light-emitting layer has a firstside facing the flexible substrate and an opposing side, athin-film-encapsulation layer is formed on the opposing side of theorganic light-emitting of the flexible substrate (S1130). Thecorresponding structure is shown in FIG. 11B.

As shown in FIG. 11B, the organic light-emitting layer 12 may have afirst side facing the flexible substrate 11 and an opposing side. Thethin-film-encapsulation layer 13 may be formed on the opposing side ofthe organic light-emitting layer 12. The thin-film-encapsulation layer13 may include at least one organic encapsulation layer 132 and at leastone inorganic encapsulation layer 131. The inorganic encapsulation layer131 may have a first side facing the flexible substrate 11 and anopposing side. The fabricated flexible display panel may include atleast one bending area, and at least one groove 14 may be formed on theopposing side of at least one inorganic encapsulation layer 131 in thebending area.

The bottom width W of the groove 14 may be configured to be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$where

is a maximum bending angle of the bending area, 0°<

≤180°, and R is a bending radius of the bending area. In one embodiment,the bottom width W of the groove 14 may be configured to be W≥πR.

In the disclosed embodiments, the organic encapsulation layer 132 mayformed by an ink jet printing process. The inorganic encapsulation layer131 may be formed by a chemical vapor deposition (CVD) process or anatomic layer deposition (ALD) process, and the groove 14 on theinorganic encapsulation layer 131 may be formed by etching.

FIG. 11C illustrates a flow chart of another exemplary fabricationmethod for an exemplary flexible display panel according to disclosedembodiments. The corresponding structure is shown in FIG. 8D.

As shown in FIG. 11C, at the beginning, a flexible substrate is provided(S1111). After the flexible substrate is provided, athin-film-transistor layer is formed on a side of the flexible substrate(S1112). In particular, the thin-film-transistor layer may include aplurality of thin-film-transistors. Each thin-film-transistor mayinclude a gate electrode, a semiconductor active layer, a sourceelectrode and a drain electrode (i.e., source-drain electrode) and atleast one insulating layer. The at least one insulating layer may have afirst side facing the flexible substrate and an opposing side. In thebending area S, at least one groove may be formed on the opposing sideof the at least one insulating layer. The bottom width W of the groove14 may be configured to be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$where n is a maximum bending angle of the bending area, 0°<

≤180°, and R is a bending radius of the bending area. In one embodiment,the bottom width W of the groove 14 may be configured to be W≥πR.

In particular, the at least one insulating layer of thethin-film-transistor layer may include a gate insulating layer and apassivation layer. The gate insulating layer may be disposed between thegate electrode and the source-drain electrode. The passivation layer maybe disposed on the gate insulating layer and the gate electrode. Thatis, in the bending area, at least one groove may be formed on theopposing side of at least one of the passivation layer and the gateinsulating layer.

After the groove is formed on the opposing side of the passivation layerin the bending area, a planarization layer is formed on thethin-film-transistor layer (S1113). After the planarization layer isformed on the thin-film-transistor layer, an organic light-emittinglayer is formed on the planarization layer (S1114). After the organiclight-emitting layer is formed on the planarization layer, athin-film-encapsulation layer is formed on the organic light-emittinglayer (S1115).

FIG. 11D illustrates a flow chart of another exemplary fabricationmethod for an exemplary flexible display panel according to disclosedembodiments. The corresponding structure is shown in FIG. 8A.

As shown in FIG. 11D, at the beginning, a flexible substrate is provided(S1121). After the flexible substrate is provided, athin-film-transistor layer is formed on a side of the flexible substrate(S1122). After the thin-film-transistor layer is formed on the flexiblesubstrate, a planarization layer is formed on the thin-film-transistorlayer, and the planarization layer has a first side facing the flexiblesubstrate and an opposing side, and at least one groove is formed on theopposing side of the planarization layer in the bending area (S1123).The bottom width W of the groove 14 may be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$configured to be where n is a maximum bending angle of the bending area,0°<

≤180°, and R is a bending radius of the bending area. In one embodiment,the bottom width W of the groove 14 may be configured to be W≥πR.

After the groove is formed on the opposing side of the planarizationlayer in the bending area, an organic light-emitting layer is formed onthe planarization layer (S1124). After the organic light-emitting layeris formed on the planarization layer, a thin-film-encapsulation layer isformed on the organic light-emitting layer (S1125).

FIG. 12 illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. As shown in FIG. 12,the flexible display panel may include a flexible substrate 11 and afirst buffer layer 191 disposed on one side of the flexible substrate11. The first buffer layer 191 may have a side away from the flexiblesubstrate 11. The flexible display panel may further include a thin-filmtransistor layer 18 disposed on the side of the first buffer layer 191away from the flexible substrate 11, and the thin-film transistor layer18 may have a side away from the flexible substrate 11. The flexibledisplay panel may further include a planarization layer 15 disposed onthe side of the thin-film transistor layer 18 away from the flexiblesubstrate 11, and the planarization layer 15 may have a side away fromthe flexible substrate 11. The flexible display panel may furtherinclude an organic light-emitting layer 12 disposed on the side of theplanarization layer 15 away from the flexible substrate 11.

The flexible display panel may include at least one bending area S. Inthe at least one bending area S, at least one groove 14 may be formed inat least one of the first buffer layer 191 and the thin-film transistorlayer 18. A bottom width W of the at least one groove 14 may beconfigured to be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$where n is a maximum bending angle of the at least one bending area S,0°<

≤180°, and R is a bending radius of the at least one bending area S.

In the disclosed embodiments, because at least one groove 14 may beformed in at least one of the first buffer layer 191 and the thin-filmtransistor layer 18, the thickness of the flexible display panel at thebending area S may be reduced and, accordingly, the bending stressgenerated in the bending area S of the flexible display panel may bereduced, thereby attenuating the risks of generating cracks or evenbreakages during the bending of the flexible display panel. Moreover,when the bottom width W of the groove 14 is configured to be

${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$the bending stress generated in the bending area S of the flexibledisplay panel may not be concentrated at the groove 14 and, accordingly,the intensity of the bending stress may be reduced, and certain portionsof the bending stress in the groove 14 may be relieved.

Although the groove 14 may be formed in the first buffer layer 191 asshown in FIG. 12, it should be noted that it is merely for illustrativepurposes without any intention to limit the scope of the invention.

In some of the optional embodiments, the bottom width W of the at leastone groove 14 may be configured to be W≥πR, such that corners of thegroove 14 may be arranged outside the bending area S, and the stress maybe prevented from being concentrated at the corners of the groove 14.Accordingly, cracks and breaks may be suppressed at the corners of thegroove 14.

In some of the optional embodiments, the bending radius R may be greaterthan or equal to approximately 0.1 mm. With reference to FIG. 1C, thebending radius R may be defined as a shortest distance between a centerof an arc formed by the bending of the bending area S and the bottom ofthe groove 14, where R may be greater than or equal to about 0.1 mm.When the bending radius R is smaller than 0.1 mm, the flexible displaypanel may not be bent easily. Excessive bending stress may occur in thebending area S, thereby increasing the risk of the flexible displaypanel breakage. When the bending radius R is greater than or equal to0.1 mm, the bending stress in the bending area S may be substantiallysmall, thereby reducing the risk of the flexible display panel breakage.

With reference to FIG. 12, optionally, a depth D of the groove 14 may besmaller than or equal to a thickness T of a non-recessed area of thelayer where the groove 14 is formed, such that the thickness of theflexible display panel at the bending area S may be reduced and,accordingly, the bending stress generated in the bending area S of theflexible display panel may be reduced, thereby avoiding the increase inthe bending radius due to the large thickness of the bending area S.

In some of the optional embodiments, the at least one groove may beformed in the first buffer layer in the bending area S. Along adirection perpendicular to a plane of the flexible display panel, the atleast one groove may pass through the first buffer layer.

As shown in FIG. 13, the groove 14 may be formed in the first bufferlayer 191. Along a direction Z perpendicular to a plane of the flexibledisplay panel, the groove 14 may pass through the first buffer layer191. The first buffer layer 191 may be formed on the flexible substrate11, attenuating or avoiding any influence on the flexible substrate 11from the high temperature manufacturing process when forming subsequentlayers on the substrate 11. Furthermore, the first buffer layer 191 mayreduce the influence on the thin-film transistor layer 18 due to ionicimpurity substances, water and oxygen from external environment. Sincethe first buffer layer 191 is commonly formed using inorganic materials,a substantially large bending stress may be generated in the firstbuffer layer 191 when the bending area is bended, which may increase therisks of generating cracks or breakages in the flexible display panel.The arrangement of the grooves passing through the first buffer layermay reduce the thickness of the flexible display panel at the bendingarea, thereby reducing the risks of generating cracks or breakages inthe display panel. When formed in the first buffer layer, optionally,the groove may be located in a non-display area of the flexible displaypanel, thereby reducing any influence on the elements located in adisplay area.

In some of the optional embodiments, the first buffer layer may be madeof a material including one of silicon oxide and silicon nitride.Alternatively, the first buffer layer may include a composite layercontaining silicon oxide and silicon nitride.

FIG. 14 illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. As shown in FIG. 14,the thin-film transistor layer 18 of the flexible display panel mayinclude a plurality of thin-film transistors 181. A thin-film transistor181 may include a semiconductor active layer 113, a gate electrode 111,a source-drain electrode 114, a gate insulating layer 112 disposedbetween the semiconductor active layer 113 and the gate electrode 111,and an interlayer insulating layer 115 (similar to the passivation layerdisclosed in aforementioned embodiments) disposed between the gateelectrode 111 and the source-drain electrode 114.

In the bending area S, the groove 14 may be formed in the gateinsulating layer 112. Along a direction Z perpendicular to a plane ofthe flexible display panel, the groove 14 may pass through the gateinsulating layer 112.

In the bending area S, the groove 14 may be formed in the interlayerinsulating layer 115. Along the direction Z perpendicular to the planeof the flexible display panel, the groove 14 may pass through theinterlayer-insulating layer 115.

As shown in FIG. 14, the thin-film transistor 181 may be exemplified bya top-gate type thin-film transistor. The thin-film transistor layer 18may include a plurality of insulating layers, for example, the gateinsulating layer 112 disposed between the semiconductor active layer 113and the gate electrode 111, and the interlayer insulating layer 115disposed between the gate electrode 111 and the source-drain electrode114, etc. Along the direction Z perpendicular to the plane of theflexible display panel, the gate insulating layer 112 and theinterlayer-insulating layer 115 may include some portions which do notoverlap with the semiconductor active layer 113, the gate electrode 111or the source-drain electrode 114. Accordingly, these portions of thegate insulating layer 112 and the interlayer-insulating layer 115 maycommonly be in contact with each other. That is, within a partial areaof the thin-film transistor layer 18, the gate insulating layer 112 andthe interlayer-insulating layer 115 may be stacked sequentially and incontact with each other. Since both the gate insulating layer 112 andthe interlayer-insulating layer 115 are commonly formed using inorganicmaterials, the portions where the two layers are stacked sequentiallyand in contact with each other are located within the bending area S, asubstantially large bending stress may be generated when the displaypanel is bended, causing the formation of cracks in the display panel.According to the embodiments of the present disclosure, in the bendingarea S, the groove 14 may be formed in the gate insulating layer 112,and along the direction Z perpendicular to the plane of the flexibledisplay panel, the groove 14 may pass through the gate insulating layer112. The groove 14 may also be formed in the interlayer-insulating layer115, and along the direction Z perpendicular to the plane of theflexible display panel, the groove 14 may pass through the interlayerinsulating layer 115. On one side, the thickness of the flexible displaypanel at the bending area S and the bending stress generated in thebending area S may be reduced, thereby realizing the bending of theflexible display panel. On the other, the occurrence of sequentialstacking and direct contact among multiple layers of inorganic materialsmay be reduced, thereby avoiding the generation of cracks and breakagesat the bending area of the flexible display panel.

Although the groove 14 may be formed in both the gate insulating layer112 and the interlayer insulating layer 115 as shown in FIG. 14, itshould be noted that it is merely for illustrative purposes withoutlimiting the scope of the invention. The groove 14 may only be formed inthe gate insulating layer 112. Alternatively, the groove may only beformed in the interlayer-insulating layer 115.

FIG. 14 also illustrates the structures of an organic light-emittinglayer. The organic light-emitting layer 12 may include a plurality oforganic light-emitting elements 121 (only one organic light-emittingelement illustrated in FIG. 14). An organic light-emitting element 121may include a first electrode 117 (e.g., a non-transparent anode or areflective anode), a pixel defining layer 125, an organic light-emittingmaterial layer 123 and a second electrode 119 (e.g., a cathode). Theorganic light-emitting material layer 123 may be disposed between thefirst electrode 117 and the second electrode 119. The pixel defininglayer 125 may be disposed on the planarization layer 15 and have anopening exposing the first electrode 117. The organic light-emittingmaterial layer 123 may be formed in a pixel defined by the pixeldefining layer 125 and correspond to the opening. Each pixel may includeone organic light-emitting element 121, and each organic light-emittingelement 121 may form a light-emitting pixel 17.

FIG. 15 illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. As shown in FIG. 15,the thin-film transistor layer 18 of the flexible display panel mayinclude a plurality of capacitors C and an interlayer dielectric layer192. A capacitor C may include two plates C1 and C2 oppositely disposed,and the interlayer dielectric layer 192 may be disposed between the gateelectrode 111 and a layer where one of the two plates of the capacitor C(e.g., plate C1 as shown in FIG. 15) is disposed. In the bending area S,the groove 14 may be formed in the interlayer dielectric layer 192.

The similarities between FIG. 15 and FIG. 14 are not repeated herein,while certain differences there-between will be explained. The flexibledisplay panel as shown in FIG. 15 may include a capacitor C, and aninterlayer dielectric layer 192 disposed between the two plates C1 andC2 of the capacitor C. The interlayer dielectric layer 192 may be madeof inorganic materials. In some of the optional embodiments, theinterlayer dielectric layer 192 may include one of silicon oxide andsilicon nitride, or may include a composite layer containing bothsilicon oxide and silicon nitride. The thin-film transistor layer 18 mayinclude a plurality of layers made of inorganic materials. In addition,within a partial area of the thin-film transistor layer 18, theplurality of layers made of inorganic materials may be stackedsequentially and in contact with each other. For example, in certainareas of the thin-film transistor layer 18 which are not covered byorthogonal projections of the semiconductor active layer 113, the gateelectrode 111 and the source-drain electrode 114 onto the flexibledisplay panel, the interlayer dielectric layer 192, the gate insulatinglayer 112, and the interlayer-insulating layer 115 may be stackedsequentially and in contact with each other. When the flexible displaypanel is bended in these areas, a substantially large bending stress maybe generated, causing the formation of cracks. In the embodiments of thepresent disclosure, the groove 14 may be formed in the interlayerdielectric layer 192, such that the thickness of the flexible displaypanel at the bending area S may be reduced, and the bending stressgenerated in the bending area S of the flexible display panel may alsobe reduced, thereby realizing the bending of the flexible display panel.

Optionally referring to FIG. 15, the groove 14 may pass through theinterlayer dielectric layer 192 along the direction Z perpendicular tothe plane of the flexible display panel. Accordingly, the occurrence ofsequential stacking and direct contact among multiple layers ofinorganic materials may be reduced, thereby avoiding the generation ofcracks and breakages at the bending area of the flexible display panel.

FIG. 16 illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. The similaritiesbetween FIG. 16 and FIG. 15 are not repeated here, while certaindifferences will be explained. The flexible display panel as shown inFIG. 16 may further include a passivation protective layer 193 disposedbetween the thin-film transistor layer 18 and the planarization layer15. In the bending area S, the groove 14 may be formed in thepassivation protective layer 193. In some of the optional embodiments,the passivation protective layer 193 may be made of inorganic materials.Specifically, the passivation protective layer 193 may include one ofsilicon oxide and silicon nitride, or include a composite layercontaining both silicon oxide and silicon nitride. In the disclosedembodiments, the arrangement of the grooves in the passivationprotective layer 193 may reduce the thickness of the flexible displaypanel at the bending area S, and may also reduce the bending stressgenerated in the bending area S, thereby realizing the bending of theflexible display panel.

It should be noted that, in the bending area S as shown in FIG. 16, thegroove 14 may be simultaneously formed in the gate insulating layer 112,the interlayer dielectric layer 192 and the interlayer insulating layer115. As such, a stepped area with substantially large step differencemay be formed near the bending area S, caused by the gate insulatinglayer 112, the interlayer dielectric layer 192 and theinterlayer-insulating layer 115. In order to reduce or even eliminateany influence caused by this substantially large step difference, thegroove 14 may be filled with organic materials. For example, a bendingprotective layer BPL may be formed in the groove 14.

FIG. 17 illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. As shown in FIG. 17,the flexible display panel in the disclosed embodiments may furtherinclude a passivation protective layer 193, a bending protective layer194 and a power supply voltage line 195. The passivation protectivelayer 193 may be disposed between the thin-film transistor layer 18 andthe planarization layer 15. The bending protective layer 194 may bedisposed between the passivation protective layer 193 and theplanarization layer 15. The power supply voltage line 195 may bedisposed between the bending protective layer 194 and the planarizationlayer 15. In the bending area S, the groove 14 may be formed in thebending protective layer 194.

In the disclosed embodiments, the power supply voltage line 195 may bearranged using double-layer wiring. For example, the power supplyvoltage line 195 may include a portion located in the same layer as thesource-drain electrode 114, and another portion located between thebending protective layer 194 and the planarization layer 15. Sucharrangement may reduce the resistance of the power supply voltage lineand improve any influence caused by voltage drop effect. Furthermore,the groove 14 may be formed in the bending protective layer 194, suchthat the thickness at the bending area S of the flexible display paneland the bending stress may be reduced. In addition, when the wirings aredisposed in the bending area S (e.g., the wirings 196 as shown in FIG.16 and FIG. 17), the influence on the wiring 196 caused by bending maybe reduced, and the breakage of the wirings may be prevented. In some ofthe optional embodiments, the bending protective layer 194 may be madeof one or more materials including at least one of benzocyclobutene,acrylamide polymer or polyimide. Alternatively, the material may includeany combination of the above.

FIG. 18 illustrates a cross-sectional view of another exemplary flexibledisplay panel according to disclosed embodiments. As shown in FIG. 18,the flexible display panel may further include at least one of thefollowing: a bottom of the groove 14 may transition to a side wall ofthe groove 14 through a first curved line 151, and the side wall of thegroove 14 transitions to a surface located at non-recessed area of alayer where the groove 14 is disposed (e.g., the first buffer layer 191as shown in FIG. 18) through a second curved line 152.

In the disclosed embodiments, the bottom of the groove 14 may transitionto the side wall of the groove 14 through the first curved line 151,such that the transition between the bottom and the side wall of thegroove may be smooth. During the bending process, the bending stressgenerated at the bottom and the side wall of the groove may further bereduced, thereby reducing the risks of generating cracks and improvingthe bending performance of the flexible display panel.

In the disclosed embodiments, an angle α between the first curved line151 and the bottom of the groove may be approximately in a range of0°<α≤70°. In some of the optional embodiments, the angle α between thefirst curved line 151 and the bottom of the groove may be approximatelyin a range of 15°<α≤70°. When the angle α between the first curved line151 and the bottom of the groove is large, for example, in a range of70°<α≤90°, a substantially large bending stress may be generated in thegroove when the flexible display panel is bended. Furthermore, thebending stress may be concentrated in the groove, causing the generationof cracks or even breakage of the groove. When the angle α between thefirst curved line 151 and the bottom of the groove is substantiallysmall, the groove may have a large width which may cause the grooveextend to the display area of the flexible display panel. Accordingly,the light generated from the display area may have refraction andreflection, affecting the display performance of the flexible displaypanel. As such, it may be preferable to have the angle α between thefirst curved line 151 and the bottom of the groove approximately in therange of 15°<α≤70°.

In the disclosed embodiments, an angle β between the second curved line152 and the non-recessed surface of the layer where the groove isdisposed (e.g., the first buffer layer 191 as shown in FIG. 18) may beapproximately in a range of 0°<β≤60°. When the angle β is large, forexample, in a range of 60°<β≤90°, a substantially large bending stressmay be generated in the groove when the flexible display panel isbended. Furthermore, the bending stress may be concentrated in thegroove, causing the generation of cracks or even breakage of the groove.When the angle β is substantially small, the groove may have a largewidth which may cause the groove extend to the display area of theflexible display panel. Accordingly, the light generated from thedisplay area may have refraction and reflection, affecting the displayperformance of the flexible display panel. As such, it may be preferableto have the angle β between the second curved line 152 and thenon-recessed surface of the layer where the groove is disposed (e.g.,the first buffer layer 191 as shown in FIG. 18) approximately in therange of 15°<β≤45°.

In some of the optional embodiments, when the bending area includes aplurality of grooves, the grooves may be arranged in parallel in adirection perpendicular to an extension direction of a groove, withreference to the above embodiments accompanying with FIG. 3B.

In some of the optional embodiments, the flexible display panel mayinclude a display area and a non-display area surrounding the displayarea. At least one of the display area and the non-display area may beconfigured with the bending area. The display area may display imageswhile the non-display area may not.

FIG. 19 illustrates a top view of another exemplary flexible displaypanel according to disclosed embodiments. As shown in FIG. 19, theflexible display panel may include a display area B1 and a non-displayarea B2 surrounding the display area B1. At least one of the displayarea B1 and the non-display area B2 may be configured with the bendingarea. For illustrative purposes only, a bending area S may be configuredin the non-display area B2 as shown in FIG. 19.

Further referring to FIG. 19, the non-display area B2 may include awiring region B21 and a binding region B22. The display area B1 mayinclude a plurality of signal lines 196. At least a portion of thesignal lines 196 may extend from the display area B1 to the bindingregion B22 through the wiring region B21. The bending area S may belocated in the wiring region B21.

The plurality of signal lines 196 disposed in the display area B1 mayinclude a plurality of data lines. When the flexible display panel wasbended at the wiring region B21, the wirings 196 located at the bendingarea S may have breakage under the bending stress. In the disclosedembodiments, by arranging the bending area S with grooves 14 at thewiring region B21, the bending stress generated at the wiring region B21may be effectively decreased, thereby reducing the risks of wiringbreakage. The specific arrangements of multiple layers within thebending area S may be referred to FIGS. 12-18.

When the flexible display panel is incorporated in a display apparatus,the bending area S may be bent, such that the non-display area B2 maybecome a side wall of the display apparatus, or the non-display area B2may be folded to the back wall of the display area B1. Thus, aborderless design of the display apparatus may be achieved, and thenon-display area B2 may be called an edge area or border area.

Further referring to FIG. 19, a binding pin may be arranged in thebinding region B22. Alternatively, an integrated circuit 197 may bearranged in the binding region B22, providing display signals to thewirings 196.

In some of the optional embodiments, the display area may include twodisplay sections, and the bending area may be disposed between twoadjacent display sections. As shown in FIG. 18, the flexible displaypanel may have a display area A including a first display section A1 anda second display section A2. Both the first display section A1 and thesecond display section A2 may be adjacent to the bending area S, and thebending area S may be disposed between the first display section A1 andthe second display section A2. That is, the bending area S may also bedisposed in the display area A, though the bending area S may be locatedin a non-light-emitting area of the display area A. In particular, anorthogonal projection of the groove 14 onto the organic light-emittinglayer 12 may be located between two adjacent rows or two adjacentcolumns of sub-pixels. The grooves 14 may be disposed betweensub-pixels. That is, in a direction perpendicular to the flexibledisplay panel, the areas where the sub-pixels are arranged may not beconfigured with any groove. Thus, the layer including the areas wherethe sub-pixels are arranged may be substantially flat, such that theoptical properties of the sub-pixels may not be influenced by the groove14.

For illustrative purposes, the first display section A1 and the seconddisplay section A2 may display different images. The bending area S maybe disposed between the first display section A1 and the second displaysection A2. That is, the bending area S may bend downwards from an edgeof the first display section A1. The bending area S may be a non-displayarea. The second display section A2 may be an area extended outward fromthe bending area S. In various practical applications, when the flexibledisplay panel is incorporated in a display apparatus, the flexibledisplay panel may display different images in the first display sectionA1 and the second display section A2. Thus, the display apparatus may bea double-sided display apparatus.

With reference to FIG. 10, a display apparatus may be provided in thepresent disclosure, including a flexible display panel according to anyone of the aforementioned embodiments.

It should be noted that the various embodiments in the presentspecification are described in a progressive manner. Each embodiment ismainly described in terms of differences from the previously describedembodiments. The similarities between different embodiments are notrepeated, and may be incorporated by references.

Various embodiments have been described to illustrate the operationprinciples and exemplary implementations. It should be understood bythose skilled in the art that the present invention is not limited tothe specific embodiments described herein and that various other obviouschanges, rearrangements, and substitutions will occur to those skilledin the art without departing from the scope of the invention. Thus,while the present invention has been described in detail with referenceto the above described embodiments, the present invention is not limitedto the above described embodiments, but may be embodied in otherequivalent forms without departing from the scope of the presentinvention, which is determined by the appended claims.

What is claimed is:
 1. A flexible display panel, comprising: a flexiblesubstrate; a first buffer layer disposed on one side of the flexiblesubstrate; a thin-film transistor layer disposed on a side of the firstbuffer layer away from the flexible substrate; a planarization layerdisposed on a side of the thin-film transistor layer away from theflexible substrate; and an organic light-emitting layer disposed on aside of the planarization layer away from the flexible substrate,wherein: the flexible display panel includes at least one bending area,in the at least one bending area, at least one groove is formed in atleast one of the first buffer layer and the thin-film transistor layer,and a bottom width W of the at least one groove is set as${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$ wherein n is a maximumbending angle of the at least one bending area, 0°<n≤180°, and R is abending radius of the at least one bending area, so as to reduce athickness of the flexible display panel in the bending area and abending stress in the bending area of the flexible display panel.
 2. Theflexible display panel according to claim 1, wherein: the bottom width Wof the at least one groove is W≥πR.
 3. The flexible display panelaccording to claim 1, wherein: the bending radius R is greater than orequal to about 0.1 mm.
 4. The flexible display panel according to claim1, wherein: a depth of the at least one groove is smaller than or equalto a thickness of a non-recessed area of the at least one of the firstbuffer layer and the thin-film transistor layer where the at least onegroove is formed.
 5. The flexible display panel according to claim 1,wherein: in the at least one bending area, the at least one groove isformed in the first buffer layer, and along a direction perpendicular toa plane of the flexible display panel, the at least one groove passesthrough the first buffer layer.
 6. The flexible display panel accordingto claim 1, wherein: the first buffer layer is made of a materialincluding one of silicon oxide and silicon nitride, or the first bufferlayer includes a composite layer containing silicon oxide and siliconnitride.
 7. The flexible display panel according to claim 1, wherein:the thin-film transistor layer includes a plurality of thin-filmtransistors, a thin-film-transistor of the plurality of thin-filmtransistors includes a semiconductor active layer, a gate electrode, asource-drain electrode, a gate insulating layer disposed between thesemiconductor active layer and the gate electrode, and an interlayerinsulating layer disposed between the gate electrode and thesource-drain electrode, and in the at least one bending area, the atleast one groove is formed in at least one of the following: the gateinsulating layer, wherein the at least one groove passes through thegate insulating layer along a direction perpendicular to a plane of theflexible display panel, and the interlayer insulating layer, wherein theat least one groove passes through the interlayer insulating layer alongthe direction perpendicular to the plane of the flexible display panel.8. The flexible display panel according to claim 7, wherein: thethin-film transistor layer includes a plurality of capacitors and aninterlayer dielectric layer, one capacitor of the plurality ofcapacitors includes two plates oppositely disposed, the interlayerdielectric layer is disposed between the gate electrode and one layerwhere one of the two plates of the capacitor is disposed, and in the atleast one bending area, the at least one groove is formed in theinterlayer dielectric layer.
 9. The flexible display panel according toclaim 8, wherein: the at least one groove passes through the interlayerdielectric layer, along the direction perpendicular to the plane of theflexible display panel.
 10. The flexible display panel according toclaim 1, further comprising: a passivation protective layer disposedbetween the thin-film transistor layer and the planarization layer,wherein: in the at least one bending area, the at least one groove isformed in the passivation protective layer.
 11. The flexible displaypanel according to claim 1, further comprising: a passivation protectivelayer; a bending protective layer; and a power supply voltage line,wherein: the passivation protective layer is disposed between thethin-film transistor layer and the planarization layer, the bendingprotective layer is disposed between the passivation protective layerand the planarization layer, at least a portion of the power supplyvoltage line is disposed between the bending protective layer and theplanarization layer, and in the at least one bending area, the at leastone groove is formed in the bending protective layer.
 12. The flexibledisplay panel according to claim 11, wherein: the bending protectivelayer is made of a material including at least one of benzocyclobutene,acrylamide polymer and polyimide.
 13. The flexible display panelaccording to claim 1, wherein: the at least one bending area includes aplurality of grooves; and the plurality of the grooves is arranged inparallel in a direction perpendicular to an extension direction of theat least one groove.
 14. A display apparatus, comprising a flexibledisplay panel according to claim
 1. 15. A flexible display panel,comprising: a flexible substrate; a first buffer layer disposed on oneside of the flexible substrate; a thin-film transistor layer disposed ona side of the first buffer layer away from the flexible substrate; aplanarization layer disposed on a side of the thin-film transistor layeraway from the flexible substrate; and an organic light-emitting layerdisposed on a side of the planarization layer away from the flexiblesubstrate, wherein: the flexible display panel includes at least onebending area, in the at least one bending area, at least one groove isformed in at least one of the first buffer layer and the thin-filmtransistor layer, and ${W \geq {\frac{n}{180^{{^\circ}}}\pi\; R}},$where W is a bottom width of the at least one groove, n is a maximumbending angle of the at least one bending area, 0°<n≤180°, and R is abending radius of the at least one bending area, wherein the flexibledisplay panel further includes at least one of a first curved line and asecond curved line, wherein: a bottom of the at least one groovetransitions to a side wall of the at least one groove through the firstcurved line, and the side wall of the at least one groove transitions toa non-recessed surface of a layer where the at least one groove isdisposed through the second curved line.
 16. The flexible display panelaccording to claim 15, wherein: an angle α between the first curved lineand the bottom of the at least one groove is approximately in a range of0°<α≤70°.
 17. The flexible display panel according to claim 16, wherein:an angle β between the second curved line and the non-recessed surfaceof the layer where the at least one groove is disposed is approximatelyin a range of 0°<β≤60°.
 18. The flexible display panel according toclaim 17, wherein: the angle β between the second curved line and thenon-recessed surface of the layer where the at least one groove isdisposed is approximately in a range of 15°<β≤45°.
 19. The flexibledisplay panel according to claim 16, wherein: the angle α between thefirst curved line and the bottom of the at least one groove isapproximately in a range of 15°<α≤70°.
 20. A flexible display panel,comprising: a flexible substrate; a first buffer layer disposed on oneside of the flexible substrate; a thin-film transistor layer disposed ona side of the first buffer layer away from the flexible substrate; aplanarization layer disposed on a side of the thin-film transistor layeraway from the flexible substrate; an organic light-emitting layerdisposed on a side of the planarization layer away from the flexiblesubstrate; and a display area and a non-display area surrounding thedisplay area, wherein the flexible display panel includes at least onebending area, and at least one of the display area and the non-displayarea is configured with the at least one bending area, wherein: in theat least one bending area, at least one groove is formed in at least oneof the first buffer layer and the thin-film transistor layer, and$W \geq {\frac{n}{180^{{^\circ}}}\pi\;{R.}}$ where W is a bottom widthof the at least one groove, n is a maximum bending angle of the at leastone bending area, 0°<n≤180°, and R is a bending radius of the at leastone bending area, wherein: the non-display area includes a wiring regionand a binding region, the display area includes a plurality of signallines, at least a portion of the plurality of signal lines extend fromthe display area to the binding region through the wiring region, andthe at least one bending area is located in the wiring region.
 21. Theflexible display panel according to claim 20, wherein: the display areaincludes at least two display sections; and the at least one bendingarea is disposed between adjacent display sections.
 22. The flexibledisplay panel according to claim 20, wherein: an orthogonal projectionof the at least one groove onto the organic light-emitting layer islocated between two adjacent rows or two adjacent columns of sub-pixels.